diff --git a/src/test/bench/core-map.rs b/src/test/bench/core-map.rs
index 730b175a49944..3bd0157c48a56 100644
--- a/src/test/bench/core-map.rs
+++ b/src/test/bench/core-map.rs
@@ -24,7 +24,7 @@ fn timed(label: &str, f: &fn()) {
     let start = time::precise_time_s();
     f();
     let end = time::precise_time_s();
-    io::println(fmt!("  %s: %f", label, end - start));
+    printfln!("  %s: %f", label, end - start);
 }
 
 fn ascending<M: MutableMap<uint, uint>>(map: &mut M, n_keys: uint) {
@@ -116,7 +116,7 @@ fn main() {
         }
     }
 
-    io::println(fmt!("%? keys", n_keys));
+    printfln!("%? keys", n_keys);
 
     io::println("\nTreeMap:");
 
diff --git a/src/test/bench/core-std.rs b/src/test/bench/core-std.rs
index ea5aa309dc6c9..0d93bdb6f9446 100644
--- a/src/test/bench/core-std.rs
+++ b/src/test/bench/core-std.rs
@@ -58,7 +58,7 @@ fn maybe_run_test(argv: &[~str], name: ~str, test: &fn()) {
     test();
     let stop = precise_time_s();
 
-    io::println(fmt!("%s:\t\t%f ms", name, (stop - start) * 1000f));
+    printfln!("%s:\t\t%f ms", name, (stop - start) * 1000f);
 }
 
 fn shift_push() {
diff --git a/src/test/bench/msgsend-ring-mutex-arcs.rs b/src/test/bench/msgsend-ring-mutex-arcs.rs
index 86784c0b7d3bc..0fa641e395eee 100644
--- a/src/test/bench/msgsend-ring-mutex-arcs.rs
+++ b/src/test/bench/msgsend-ring-mutex-arcs.rs
@@ -119,8 +119,7 @@ fn main() {
     let elapsed = (stop - start);
     let rate = (num_msgs as float) / elapsed;
 
-    io::println(fmt!("Sent %? messages in %? seconds",
-                     num_msgs, elapsed));
-    io::println(fmt!("  %? messages / second", rate));
-    io::println(fmt!("  %? μs / message", 1000000. / rate));
+    printfln!("Sent %? messages in %? seconds", num_msgs, elapsed);
+    printfln!("  %? messages / second", rate);
+    printfln!("  %? μs / message", 1000000. / rate);
 }
diff --git a/src/test/bench/msgsend-ring-pipes.rs b/src/test/bench/msgsend-ring-pipes.rs
index b79f171147aa0..9eb415e889233 100644
--- a/src/test/bench/msgsend-ring-pipes.rs
+++ b/src/test/bench/msgsend-ring-pipes.rs
@@ -105,8 +105,7 @@ fn main() {
     let elapsed = (stop - start);
     let rate = (num_msgs as float) / elapsed;
 
-    io::println(fmt!("Sent %? messages in %? seconds",
-                     num_msgs, elapsed));
-    io::println(fmt!("  %? messages / second", rate));
-    io::println(fmt!("  %? μs / message", 1000000. / rate));
+    printfln!("Sent %? messages in %? seconds", num_msgs, elapsed);
+    printfln!("  %? messages / second", rate);
+    printfln!("  %? μs / message", 1000000. / rate);
 }
diff --git a/src/test/bench/msgsend-ring-rw-arcs.rs b/src/test/bench/msgsend-ring-rw-arcs.rs
index b4037d866a010..09d1c632d0e48 100644
--- a/src/test/bench/msgsend-ring-rw-arcs.rs
+++ b/src/test/bench/msgsend-ring-rw-arcs.rs
@@ -115,8 +115,7 @@ fn main() {
     let elapsed = (stop - start);
     let rate = (num_msgs as float) / elapsed;
 
-    io::println(fmt!("Sent %? messages in %? seconds",
-                     num_msgs, elapsed));
-    io::println(fmt!("  %? messages / second", rate));
-    io::println(fmt!("  %? μs / message", 1000000. / rate));
+    printfln!("Sent %? messages in %? seconds", num_msgs, elapsed);
+    printfln!("  %? messages / second", rate);
+    printfln!("  %? μs / message", 1000000. / rate);
 }
diff --git a/src/test/bench/pingpong.rs b/src/test/bench/pingpong.rs
index 2eb274378900a..b11daeef12f51 100644
--- a/src/test/bench/pingpong.rs
+++ b/src/test/bench/pingpong.rs
@@ -198,13 +198,13 @@ fn main() {
     let bounded = do timeit { bounded(count) };
     let unbounded = do timeit { unbounded(count) };
 
-    io::println(fmt!("count: %?\n", count));
-    io::println(fmt!("bounded:   %? s\t(%? μs/message)",
-                     bounded, bounded * 1000000. / (count as float)));
-    io::println(fmt!("unbounded: %? s\t(%? μs/message)",
-                     unbounded, unbounded * 1000000. / (count as float)));
-
-    io::println(fmt!("\n\
-                      bounded is %?%% faster",
-                     (unbounded - bounded) / bounded * 100.));
+    printfln!("count: %?\n", count);
+    printfln!("bounded:   %? s\t(%? μs/message)",
+              bounded, bounded * 1000000. / (count as float));
+    printfln!("unbounded: %? s\t(%? μs/message)",
+              unbounded, unbounded * 1000000. / (count as float));
+
+    printfln!("\n\
+               bounded is %?%% faster",
+              (unbounded - bounded) / bounded * 100.);
 }
diff --git a/src/test/bench/shootout-ackermann.rs b/src/test/bench/shootout-ackermann.rs
index ff806c8b5d44d..e06ff02a0b38f 100644
--- a/src/test/bench/shootout-ackermann.rs
+++ b/src/test/bench/shootout-ackermann.rs
@@ -36,5 +36,5 @@ fn main() {
         args
     };
     let n = int::from_str(args[1]).get();
-    io::println(fmt!("Ack(3,%d): %d\n", n, ack(3, n)));
+    printfln!("Ack(3,%d): %d\n", n, ack(3, n));
 }
diff --git a/src/test/bench/shootout-binarytrees.rs b/src/test/bench/shootout-binarytrees.rs
index d88843e118045..2f63c302d534d 100644
--- a/src/test/bench/shootout-binarytrees.rs
+++ b/src/test/bench/shootout-binarytrees.rs
@@ -61,9 +61,9 @@ fn main() {
     let stretch_depth = max_depth + 1;
     let stretch_tree = bottom_up_tree(&stretch_arena, 0, stretch_depth);
 
-    println(fmt!("stretch tree of depth %d\t check: %d",
-                          stretch_depth,
-                          item_check(stretch_tree)));
+    printfln!("stretch tree of depth %d\t check: %d",
+              stretch_depth,
+              item_check(stretch_tree));
 
     let long_lived_arena = arena::Arena();
     let long_lived_tree = bottom_up_tree(&long_lived_arena, 0, max_depth);
@@ -79,12 +79,11 @@ fn main() {
             chk += item_check(temp_tree);
             i += 1;
         }
-        println(fmt!("%d\t trees of depth %d\t check: %d",
-                         iterations * 2, depth,
-                         chk));
+        printfln!("%d\t trees of depth %d\t check: %d",
+                  iterations * 2, depth, chk));
         depth += 2;
     }
-    println(fmt!("long lived tree of depth %d\t check: %d",
-                     max_depth,
-                     item_check(long_lived_tree)));
+    printfln!("long lived tree of depth %d\t check: %d",
+              max_depth,
+              item_check(long_lived_tree));
 }
diff --git a/src/test/bench/shootout-fannkuch-redux.rs b/src/test/bench/shootout-fannkuch-redux.rs
index 1d2095df9dfd5..97c2cba3b9e31 100644
--- a/src/test/bench/shootout-fannkuch-redux.rs
+++ b/src/test/bench/shootout-fannkuch-redux.rs
@@ -93,5 +93,5 @@ fn fannkuch_redux(n: i32) -> i32 {
 #[fixed_stack_segment]
 fn main() {
     let n: i32 = FromStr::from_str(os::args()[1]).get();
-    println(fmt!("Pfannkuchen(%d) = %d", n as int, fannkuch_redux(n) as int));
+    printfln!("Pfannkuchen(%d) = %d", n as int, fannkuch_redux(n) as int);
 }
diff --git a/src/test/bench/shootout-fibo.rs b/src/test/bench/shootout-fibo.rs
index de36a59dd6507..7b8bc31bf1c83 100644
--- a/src/test/bench/shootout-fibo.rs
+++ b/src/test/bench/shootout-fibo.rs
@@ -32,5 +32,5 @@ fn main() {
         args
     };
     let n = int::from_str(args[1]).get();
-    io::println(fmt!("%d\n", fib(n)));
+    printfln!("%d\n", fib(n));
 }
diff --git a/src/test/bench/shootout-k-nucleotide.rs b/src/test/bench/shootout-k-nucleotide.rs
index 405aa68c483ba..a7b784e1a96e8 100644
--- a/src/test/bench/shootout-k-nucleotide.rs
+++ b/src/test/bench/shootout-k-nucleotide.rs
@@ -82,7 +82,7 @@ struct PrintCallback(&'static str);
 
 impl TableCallback for PrintCallback {
     fn f(&self, entry: &mut Entry) {
-        println(fmt!("%d\t%s", entry.count as int, **self));
+        printfln!("%d\t%s", entry.count as int, **self);
     }
 }
 
@@ -279,9 +279,9 @@ fn print_frequencies(frequencies: &Table, frame: i32) {
     }
 
     for vector.each |&(key, count)| {
-        println(fmt!("%s %.3f",
-                     key.unpack(frame),
-                     (count as float * 100.0) / (total_count as float)));
+        printfln!("%s %.3f",
+                  key.unpack(frame),
+                  (count as float * 100.0) / (total_count as float));
     }
 }
 
diff --git a/src/test/bench/shootout-mandelbrot.rs b/src/test/bench/shootout-mandelbrot.rs
index b79ecd03c0c68..594593e2ea343 100644
--- a/src/test/bench/shootout-mandelbrot.rs
+++ b/src/test/bench/shootout-mandelbrot.rs
@@ -15,7 +15,7 @@ fn main() {
         let mut byte_acc: i8 = 0;
         let mut bit_num: i32 = 0;
 
-        println(fmt!("P4\n%d %d", w as int, h as int));
+        printfln!("P4\n%d %d", w as int, h as int);
 
         let mode = "w";
         let stdout = fdopen(STDOUT_FILENO as c_int, transmute(&mode[0]));
diff --git a/src/test/bench/shootout-nbody.rs b/src/test/bench/shootout-nbody.rs
index 1fab646fb37a7..6d04292588d45 100644
--- a/src/test/bench/shootout-nbody.rs
+++ b/src/test/bench/shootout-nbody.rs
@@ -142,9 +142,9 @@ fn main() {
     let mut bodies = BODIES;
 
     offset_momentum(&mut bodies);
-    println(fmt!("%.9f", energy(&bodies) as float));
+    printfln!("%.9f", energy(&bodies) as float);
 
     advance(&mut bodies, 0.01, n);
 
-    println(fmt!("%.9f", energy(&bodies) as float));
+    printfln!("%.9f", energy(&bodies) as float);
 }
diff --git a/src/test/bench/shootout-spectralnorm.rs b/src/test/bench/shootout-spectralnorm.rs
index 3e3df53eaad97..388613482c2cf 100644
--- a/src/test/bench/shootout-spectralnorm.rs
+++ b/src/test/bench/shootout-spectralnorm.rs
@@ -61,5 +61,5 @@ fn main() {
         mult_AtAv(v, u, tmp);
     }
 
-    println(fmt!("%.9f", (dot(u,v) / dot(v,v)).sqrt() as float));
+    printfln!("%.9f", (dot(u,v) / dot(v,v)).sqrt() as float);
 }
diff --git a/src/test/bench/shootout-threadring.rs b/src/test/bench/shootout-threadring.rs
index 7e75ac8584855..203b9c297fa6b 100644
--- a/src/test/bench/shootout-threadring.rs
+++ b/src/test/bench/shootout-threadring.rs
@@ -40,7 +40,7 @@ fn roundtrip(id: int, n_tasks: int, p: &Port<int>, ch: &Chan<int>) {
     while (true) {
         match p.recv() {
           1 => {
-            println(fmt!("%d\n", id));
+            printfln!("%d\n", id);
             return;
           }
           token => {
diff --git a/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs b/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
index e2fbce6e195f5..9a82dd3f512ca 100644
--- a/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
+++ b/src/test/compile-fail/borrowck-auto-mut-ref-to-immut-var.rs
@@ -18,7 +18,7 @@ struct Foo {
 
 impl Foo {
     pub fn printme(&mut self) {
-        io::println(fmt!("%d", self.x));
+        printfln!("%d", self.x);
     }
 }
 
diff --git a/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs b/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
index c02a0b4cfafd5..e3e12a4a4168b 100644
--- a/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
+++ b/src/test/compile-fail/borrowck-vec-pattern-tail-element-loan.rs
@@ -9,5 +9,5 @@ fn a() -> &int {
 
 fn main() {
     let fifth = a();
-    println(fmt!("%d", *fifth));
+    printfln!("%d", *fifth);
 }
diff --git a/src/test/compile-fail/issue-3820.rs b/src/test/compile-fail/issue-3820.rs
index 8fafd04d1e2a5..04c3a0624264d 100644
--- a/src/test/compile-fail/issue-3820.rs
+++ b/src/test/compile-fail/issue-3820.rs
@@ -22,5 +22,5 @@ fn main() {
     let u = Thing {x: 2};
     let _v = u.mul(&3); // This is ok
     let w = u * 3; //~ ERROR binary operation * cannot be applied to type `Thing`
-    println(fmt!("%i", w.x));
+    printfln!("%i", w.x);
 }
diff --git a/src/test/compile-fail/issue-4335.rs b/src/test/compile-fail/issue-4335.rs
index ffa11e592608d..9ec1f5cd441b0 100644
--- a/src/test/compile-fail/issue-4335.rs
+++ b/src/test/compile-fail/issue-4335.rs
@@ -14,5 +14,5 @@ fn f<'r, T>(v: &'r T) -> &'r fn()->T { id::<&'r fn()->T>(|| *v) } //~ ERROR cann
 
 fn main() {
     let v = &5;
-    println(fmt!("%d", f(v)()));
+    printfln!("%d", f(v)());
 }
diff --git a/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs b/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
index f05c30c3355e0..19a3ce4f8384b 100644
--- a/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
+++ b/src/test/compile-fail/moves-based-on-type-no-recursive-stack-closure.rs
@@ -28,7 +28,7 @@ fn innocent_looking_victim() {
             match x {
                 Some(ref msg) => {
                     (f.c)(f, true);
-                    println(fmt!("%?", msg));
+                    printfln!(msg);
                 },
                 None => fail!("oops"),
             }
diff --git a/src/test/compile-fail/tuple-struct-nonexhaustive.rs b/src/test/compile-fail/tuple-struct-nonexhaustive.rs
index 785eeb24784fa..4640957a9a894 100644
--- a/src/test/compile-fail/tuple-struct-nonexhaustive.rs
+++ b/src/test/compile-fail/tuple-struct-nonexhaustive.rs
@@ -13,7 +13,7 @@ struct Foo(int, int);
 fn main() {
     let x = Foo(1, 2);
     match x {   //~ ERROR non-exhaustive
-        Foo(1, b) => println(fmt!("%d", b)),
-        Foo(2, b) => println(fmt!("%d", b))
+        Foo(1, b) => printfln!("%d", b),
+        Foo(2, b) => printfln!("%d", b)
     }
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
index 91df90f8b3ac9..8ed3297e7d142 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slice-method.rs
@@ -33,5 +33,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(z.my_mut_slice(), z2.my_slice());
-    print(fmt!("%d\n", z[0]));
+    printfln!("%d", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
index bae693ce4eae2..d2971ad40ab44 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm-slices.rs
@@ -12,5 +12,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(z, z2);
-    print(fmt!("%d\n", z[0]));
+    printfln!("%d", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs b/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
index 9e2a02b32dfed..df096e8292f82 100644
--- a/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
+++ b/src/test/run-fail/borrowck-wg-one-mut-one-imm.rs
@@ -13,5 +13,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&mut z[0], &z2[0]);
-    print(fmt!("%d\n", z[0]));
+    printfln!("%d", z[0]);
 }
diff --git a/src/test/run-fail/borrowck-wg-two-array-indices.rs b/src/test/run-fail/borrowck-wg-two-array-indices.rs
index ad68448876028..98bb72c93408b 100644
--- a/src/test/run-fail/borrowck-wg-two-array-indices.rs
+++ b/src/test/run-fail/borrowck-wg-two-array-indices.rs
@@ -13,5 +13,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&mut z[0], &mut z2[0]);
-    print(fmt!("%d\n", z[0]));
+    printfln!("%d", z[0]);
 }
diff --git a/src/test/run-pass/auto-ref.rs b/src/test/run-pass/auto-ref.rs
index 7171b0ee86c4b..cc14af45c85cb 100644
--- a/src/test/run-pass/auto-ref.rs
+++ b/src/test/run-pass/auto-ref.rs
@@ -18,7 +18,7 @@ trait Stuff {
 
 impl Stuff for Foo {
     fn printme(&self) {
-        println(fmt!("%d", self.x));
+        printfln!("%d", self.x);
     }
 }
 
diff --git a/src/test/run-pass/borrowck-wg-two-imm-borrows.rs b/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
index 20f824e969a48..306141354ca76 100644
--- a/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
+++ b/src/test/run-pass/borrowck-wg-two-imm-borrows.rs
@@ -10,5 +10,5 @@ pub fn main()
     let z = @mut [1,2,3];
     let z2 = z;
     add(&z[0], &z2[0]);
-    print(fmt!("%d\n", z[0]));
+    printfln!("%d", z[0]);
 }
diff --git a/src/test/run-pass/cci_impl_exe.rs b/src/test/run-pass/cci_impl_exe.rs
index 097184540fdfc..30adaf2dae4a3 100644
--- a/src/test/run-pass/cci_impl_exe.rs
+++ b/src/test/run-pass/cci_impl_exe.rs
@@ -19,7 +19,7 @@ pub fn main() {
     //info!("%?", bt0);
 
     do 3u.to(10u) |i| {
-        print(fmt!("%u\n", i));
+        printfln!("%u", i);
 
         //let bt1 = sys::frame_address();
         //info!("%?", bt1);
diff --git a/src/test/run-pass/cci_iter_exe.rs b/src/test/run-pass/cci_iter_exe.rs
index a8c0583701380..4db0b1871d078 100644
--- a/src/test/run-pass/cci_iter_exe.rs
+++ b/src/test/run-pass/cci_iter_exe.rs
@@ -17,7 +17,7 @@ pub fn main() {
     //let bt0 = sys::rusti::frame_address(1u32);
     //info!("%?", bt0);
     do cci_iter_lib::iter(~[1, 2, 3]) |i| {
-        print(fmt!("%d", *i));
+        printf!("%d", *i);
         //assert!(bt0 == sys::rusti::frame_address(2u32));
     }
 }
diff --git a/src/test/run-pass/cci_no_inline_exe.rs b/src/test/run-pass/cci_no_inline_exe.rs
index 83a77ad987736..6459239e46959 100644
--- a/src/test/run-pass/cci_no_inline_exe.rs
+++ b/src/test/run-pass/cci_no_inline_exe.rs
@@ -23,7 +23,7 @@ pub fn main() {
     //let bt0 = sys::frame_address();
     //info!("%?", bt0);
     do iter(~[1u, 2u, 3u]) |i| {
-        print(fmt!("%u\n", i));
+        printfln!("%u", i);
 
         //let bt1 = sys::frame_address();
         //info!("%?", bt1);
diff --git a/src/test/run-pass/const-fields-and-indexing.rs b/src/test/run-pass/const-fields-and-indexing.rs
index 990e5e6721915..6dca5d60f1111 100644
--- a/src/test/run-pass/const-fields-and-indexing.rs
+++ b/src/test/run-pass/const-fields-and-indexing.rs
@@ -27,9 +27,9 @@ static k : K = K {a: 10, b: 20, c: D {d: 30, e: 40}};
 static m : int = k.c.e;
 
 pub fn main() {
-    io::println(fmt!("%?", p));
-    io::println(fmt!("%?", q));
-    io::println(fmt!("%?", t));
+    printfln!(p);
+    printfln!(q);
+    printfln!(t);
     assert_eq!(p, 3);
     assert_eq!(q, 3);
     assert_eq!(t, 20);
diff --git a/src/test/run-pass/const-rec-and-tup.rs b/src/test/run-pass/const-rec-and-tup.rs
index 31b806bf41a1b..5b80988dcdfb0 100644
--- a/src/test/run-pass/const-rec-and-tup.rs
+++ b/src/test/run-pass/const-rec-and-tup.rs
@@ -21,5 +21,5 @@ static y : AnotherPair = AnotherPair{ x: (0xf0f0f0f0_f0f0f0f0,
 pub fn main() {
     let (p, _) = y.x;
     assert_eq!(p, - 1085102592571150096);
-    println(fmt!("0x%x", p as uint));
+    printfln!("0x%x", p as uint);
 }
diff --git a/src/test/run-pass/const-region-ptrs.rs b/src/test/run-pass/const-region-ptrs.rs
index cdc71292ae069..c2103a40bfea7 100644
--- a/src/test/run-pass/const-region-ptrs.rs
+++ b/src/test/run-pass/const-region-ptrs.rs
@@ -17,8 +17,8 @@ static x: &'static int = &10;
 static y: &'static Pair<'static> = &Pair {a: 15, b: x};
 
 pub fn main() {
-    io::println(fmt!("x = %?", *x));
-    io::println(fmt!("y = {a: %?, b: %?}", y.a, *(y.b)));
+    printfln!("x = %?", *x);
+    printfln!("y = {a: %?, b: %?}", y.a, *(y.b));
     assert_eq!(*x, 10);
     assert_eq!(*(y.b), 10);
 }
diff --git a/src/test/run-pass/const-struct.rs b/src/test/run-pass/const-struct.rs
index 8a93a3e4c1ccb..c62fcd8980fad 100644
--- a/src/test/run-pass/const-struct.rs
+++ b/src/test/run-pass/const-struct.rs
@@ -30,6 +30,6 @@ pub fn main() {
     assert_eq!(x.b, 2);
     assert_eq!(x, y);
     assert_eq!(z.b, 22);
-    io::println(fmt!("0x%x", x.b as uint));
-    io::println(fmt!("0x%x", z.c as uint));
+    printfln!("0x%x", x.b as uint);
+    printfln!("0x%x", z.c as uint);
 }
diff --git a/src/test/run-pass/const-vecs-and-slices.rs b/src/test/run-pass/const-vecs-and-slices.rs
index 0aee53a4ed2d2..01ef3284e32f9 100644
--- a/src/test/run-pass/const-vecs-and-slices.rs
+++ b/src/test/run-pass/const-vecs-and-slices.rs
@@ -14,8 +14,8 @@ static x : [int, ..4] = [1,2,3,4];
 static y : &'static [int] = &[1,2,3,4];
 
 pub fn main() {
-    io::println(fmt!("%?", x[1]));
-    io::println(fmt!("%?", y[1]));
+    printfln!(x[1]);
+    printfln!(y[1]);
     assert_eq!(x[1], 2);
     assert_eq!(x[3], 4);
     assert_eq!(x[3], y[3]);
diff --git a/src/test/run-pass/functional-struct-update.rs b/src/test/run-pass/functional-struct-update.rs
index 6d95f6b23ab35..0cd9b2adf7ce6 100644
--- a/src/test/run-pass/functional-struct-update.rs
+++ b/src/test/run-pass/functional-struct-update.rs
@@ -16,5 +16,5 @@ struct Foo {
 pub fn main() {
     let a = Foo { x: 1, y: 2 };
     let c = Foo { x: 4, .. a};
-    println(fmt!("%?", c));
+    printfln!(c);
 }
diff --git a/src/test/run-pass/issue-2185.rs b/src/test/run-pass/issue-2185.rs
index 5b320ddc06bb6..c84386c722da7 100644
--- a/src/test/run-pass/issue-2185.rs
+++ b/src/test/run-pass/issue-2185.rs
@@ -80,5 +80,5 @@ pub fn main() {
         a);
     let sum = foldl(filt, 0u, |accum, &&n: uint| accum + n );
 
-    io::println(fmt!("%u", sum));
+    printfln!("%u", sum);
 }
diff --git a/src/test/run-pass/issue-2989.rs b/src/test/run-pass/issue-2989.rs
index 5b3333fb998cc..d4cbfa91fb6a4 100644
--- a/src/test/run-pass/issue-2989.rs
+++ b/src/test/run-pass/issue-2989.rs
@@ -42,7 +42,7 @@ pub fn main() {
     let bools2 = to_bools(Storage{storage: ~[0b01100100]});
 
     for uint::range(0, 8) |i| {
-        io::println(fmt!("%u => %u vs %u", i, bools[i] as uint, bools2[i] as uint));
+        printfln!("%u => %u vs %u", i, bools[i] as uint, bools2[i] as uint);
     }
 
     assert_eq!(bools, bools2);
diff --git a/src/test/run-pass/issue-3211.rs b/src/test/run-pass/issue-3211.rs
index c7b0823296c67..3e3e6d6f99215 100644
--- a/src/test/run-pass/issue-3211.rs
+++ b/src/test/run-pass/issue-3211.rs
@@ -4,5 +4,5 @@ pub fn main() {
         x += 1;
     }
     assert_eq!(x, 4096);
-    println(fmt!("x = %u", x));
+    printfln!("x = %u", x);
 }
diff --git a/src/test/run-pass/issue-3743.rs b/src/test/run-pass/issue-3743.rs
index e9c2ab87c2b3d..e42b70b5a5e0d 100644
--- a/src/test/run-pass/issue-3743.rs
+++ b/src/test/run-pass/issue-3743.rs
@@ -42,11 +42,11 @@ pub fn main() {
 
     // the following compiles and works properly
     let v1: Vec2 = a * 3f;
-    io::println(fmt!("%f %f", v1.x, v1.y));
+    printfln!("%f %f", v1.x, v1.y);
 
     // the following compiles but v2 will not be Vec2 yet and
     // using it later will cause an error that the type of v2
     // must be known
     let v2 = a * 3f;
-    io::println(fmt!("%f %f", v2.x, v2.y)); // error regarding v2's type
+    printfln!("%f %f", v2.x, v2.y); // error regarding v2's type
 }
diff --git a/src/test/run-pass/issue-3753.rs b/src/test/run-pass/issue-3753.rs
index a94abe04fded2..12ec501788de8 100644
--- a/src/test/run-pass/issue-3753.rs
+++ b/src/test/run-pass/issue-3753.rs
@@ -35,5 +35,5 @@ impl Shape {
 
 pub fn main(){
     let s = Circle(Point { x: 1f, y: 2f }, 3f);
-    println(fmt!("%f", s.area(s)));
+    printfln!("%f", s.area(s));
 }
diff --git a/src/test/run-pass/issue-3794.rs b/src/test/run-pass/issue-3794.rs
index 1c1eb75c220c1..5ec8383dd20b2 100644
--- a/src/test/run-pass/issue-3794.rs
+++ b/src/test/run-pass/issue-3794.rs
@@ -19,7 +19,7 @@ struct S {
 
 impl T for S {
     fn print(&self) {
-        io::println(fmt!("%?", self));
+        printfln!(self);
     }
 }
 
diff --git a/src/test/run-pass/issue-3904.rs b/src/test/run-pass/issue-3904.rs
index 6b0796a1260d5..98b7741461ec4 100644
--- a/src/test/run-pass/issue-3904.rs
+++ b/src/test/run-pass/issue-3904.rs
@@ -12,7 +12,7 @@
 type ErrPrinter = &fn(&str, &str);
 
 fn example_err(prog: &str, arg: &str) {
-    io::println(fmt!("%s: %s", prog, arg))
+    printfln!("%s: %s", prog, arg)
 }
 
 fn exit(+print: ErrPrinter, prog: &str, arg: &str) {
diff --git a/src/test/run-pass/issue-4241.rs b/src/test/run-pass/issue-4241.rs
index 1f5da69018ab5..857ecb3f9cbcf 100644
--- a/src/test/run-pass/issue-4241.rs
+++ b/src/test/run-pass/issue-4241.rs
@@ -114,7 +114,7 @@ fn query(cmd: ~[~str], sb: TcpSocketBuf) -> Result {
   //io::println(cmd);
   sb.write_str(cmd);
   let res = parse_response(@sb as @io::Reader);
-  //io::println(fmt!("%?", res));
+  //printfln!(res);
   res
 }
 
@@ -122,7 +122,7 @@ fn query2(cmd: ~[~str]) -> Result {
   let _cmd = cmd_to_str(cmd);
     do io::with_str_reader(~"$3\r\nXXX\r\n") |sb| {
     let res = parse_response(@sb as @io::Reader);
-    io::println(fmt!("%?", res));
+    printfln!(res);
     res
     }
 }
diff --git a/src/test/run-pass/issue-4401.rs b/src/test/run-pass/issue-4401.rs
index d0d211c109c85..e993d827abb7d 100644
--- a/src/test/run-pass/issue-4401.rs
+++ b/src/test/run-pass/issue-4401.rs
@@ -4,5 +4,5 @@ pub fn main() {
         count += 1;
     }
     assert_eq!(count, 999_999);
-    println(fmt!("%u", count));
+    printfln!("%u", count);
 }
diff --git a/src/test/run-pass/max-min-classes.rs b/src/test/run-pass/max-min-classes.rs
index c34067c329d27..685a11c79ee32 100644
--- a/src/test/run-pass/max-min-classes.rs
+++ b/src/test/run-pass/max-min-classes.rs
@@ -35,5 +35,5 @@ fn Foo(x: int, y: int) -> Foo {
 
 pub fn main() {
     let foo = Foo(3, 20);
-    println(fmt!("%d %d", foo.sum(), foo.product()));
+    printfln!("%d %d", foo.sum(), foo.product());
 }
diff --git a/src/test/run-pass/new-style-constants.rs b/src/test/run-pass/new-style-constants.rs
index 2da532422c0cb..a00bfceab0f4d 100644
--- a/src/test/run-pass/new-style-constants.rs
+++ b/src/test/run-pass/new-style-constants.rs
@@ -13,5 +13,5 @@ use std::io::println;
 static FOO: int = 3;
 
 pub fn main() {
-    println(fmt!("%d", FOO));
+    printfln!("%d", FOO);
 }
diff --git a/src/test/run-pass/new-style-fixed-length-vec.rs b/src/test/run-pass/new-style-fixed-length-vec.rs
index 41704c252c8db..488bd65f5484a 100644
--- a/src/test/run-pass/new-style-fixed-length-vec.rs
+++ b/src/test/run-pass/new-style-fixed-length-vec.rs
@@ -13,5 +13,5 @@ use std::io::println;
 static FOO: [int, ..3] = [1, 2, 3];
 
 pub fn main() {
-    println(fmt!("%d %d %d", FOO[0], FOO[1], FOO[2]));
+    printfln!("%d %d %d", FOO[0], FOO[1], FOO[2]);
 }
diff --git a/src/test/run-pass/newtype.rs b/src/test/run-pass/newtype.rs
index d26210e9a4c1c..3e2308bfcaf66 100644
--- a/src/test/run-pass/newtype.rs
+++ b/src/test/run-pass/newtype.rs
@@ -16,6 +16,6 @@ fn compute(i: mytype) -> int { return i.val + 20; }
 
 pub fn main() {
     let myval = mytype(Mytype{compute: compute, val: 30});
-    println(fmt!("%d", compute(myval)));
+    printfln!("%d", compute(myval));
     assert_eq!((myval.compute)(myval), 50);
 }
diff --git a/src/test/run-pass/num-range-rev.rs b/src/test/run-pass/num-range-rev.rs
index 7262339e431d9..e40a183243e01 100644
--- a/src/test/run-pass/num-range-rev.rs
+++ b/src/test/run-pass/num-range-rev.rs
@@ -56,13 +56,13 @@ pub fn main() {
     let primes = [2,3,5,7,11];
     let mut prod = 1i;
     for uint_range_rev(5, 0) |i| {
-        println(fmt!("uint 4 downto 0: %u", i));
+        printfln!("uint 4 downto 0: %u", i);
         prod *= int::pow(primes[i], i);
     }
     assert_eq!(prod, 11*11*11*11*7*7*7*5*5*3*1);
     let mut prod = 1i;
     for int_range_rev(5, 0) |i| {
-        println(fmt!("int 4 downto 0: %d", i));
+        printfln!("int 4 downto 0: %d", i);
         prod *= int::pow(primes[i], i as uint);
     }
     assert_eq!(prod, 11*11*11*11*7*7*7*5*5*3*1);
diff --git a/src/test/run-pass/num-range.rs b/src/test/run-pass/num-range.rs
index 7c1f905a049b6..d01b22404467a 100644
--- a/src/test/run-pass/num-range.rs
+++ b/src/test/run-pass/num-range.rs
@@ -28,7 +28,7 @@ fn uint_range_step(a: uint, b: uint, s: int, it: &fn(uint) -> bool) -> bool {
 }
 
 pub fn main() {
-    println(fmt!("num-range start"));
+    println("num-range start");
     // int and uint have same result for
     //   Sum{2 <= i < 100} == (Sum{1 <= i <= 99} - 1) == n*(n+1)/2 - 1 for n=99
     let mut sum = 0u;
@@ -105,7 +105,7 @@ pub fn main() {
     let mut saw21 = false;
     for uint::range_step_inclusive(0, 21, 3) |x| {
         assert!(x <= 21);
-        println(fmt!("saw: %u", x));
+        printfln!("saw: %u", x);
         if x == 21 { saw21 = true; }
     }
     assert!(saw21);
diff --git a/src/test/run-pass/placement-new-arena.rs b/src/test/run-pass/placement-new-arena.rs
index 839f40fe67f57..9500f83b76b09 100644
--- a/src/test/run-pass/placement-new-arena.rs
+++ b/src/test/run-pass/placement-new-arena.rs
@@ -17,6 +17,6 @@ pub fn main() {
     let mut arena = arena::Arena();
     let p = &mut arena;
     let x = p.alloc(|| 4u);
-    print(fmt!("%u", *x));
+    printf!("%u", *x);
     assert_eq!(*x, 4u);
 }
diff --git a/src/test/run-pass/recursion.rs b/src/test/run-pass/recursion.rs
index 092cd3d8ed5bb..07a5c10ab1fd1 100644
--- a/src/test/run-pass/recursion.rs
+++ b/src/test/run-pass/recursion.rs
@@ -30,5 +30,5 @@ fn test<T:Dot> (n:int, i:int, first:T, second:T) ->int {
 }
 pub fn main() {
   let n = test(1, 0, Nil, Nil);
-  io::println(fmt!("%d", n));
+  printfln!("%d", n);
 }
diff --git a/src/test/run-pass/reflect-visit-data.rs b/src/test/run-pass/reflect-visit-data.rs
index 88fac13c33e8f..21d13c722e752 100644
--- a/src/test/run-pass/reflect-visit-data.rs
+++ b/src/test/run-pass/reflect-visit-data.rs
@@ -667,7 +667,7 @@ pub fn main() {
 
         let r = u.vals.clone();
         for r.iter().advance |s| {
-            println(fmt!("val: %s", *s));
+            printfln!("val: %s", *s);
         }
         error!("%?", u.vals.clone());
         assert_eq!(u.vals.clone(),
diff --git a/src/test/run-pass/reflect-visit-type.rs b/src/test/run-pass/reflect-visit-type.rs
index b3c5acd7dd5c4..dc639bad75efa 100644
--- a/src/test/run-pass/reflect-visit-type.rs
+++ b/src/test/run-pass/reflect-visit-type.rs
@@ -171,7 +171,7 @@ pub fn main() {
     visit_ty::<~[int]>(vv);
 
     for v.types.iter().advance |s| {
-        println(fmt!("type: %s", (*s).clone()));
+        printfln!("type: %s", (*s).clone());
     }
     assert_eq!((*v.types).clone(), ~[~"bool", ~"int", ~"i8", ~"i16", ~"[", ~"int", ~"]"]);
 }
diff --git a/src/test/run-pass/struct-pattern-matching.rs b/src/test/run-pass/struct-pattern-matching.rs
index 68fa137397525..3d8c2b7f56a0d 100644
--- a/src/test/run-pass/struct-pattern-matching.rs
+++ b/src/test/run-pass/struct-pattern-matching.rs
@@ -16,6 +16,6 @@ struct Foo {
 pub fn main() {
     let a = Foo { x: 1, y: 2 };
     match a {
-        Foo { x: x, y: y } => println(fmt!("yes, %d, %d", x, y))
+        Foo { x: x, y: y } => printfln!("yes, %d, %d", x, y)
     }
 }
diff --git a/src/test/run-pass/trait-inheritance-num2.rs b/src/test/run-pass/trait-inheritance-num2.rs
index bc1583a08780a..4003a83e80bb0 100644
--- a/src/test/run-pass/trait-inheritance-num2.rs
+++ b/src/test/run-pass/trait-inheritance-num2.rs
@@ -99,7 +99,7 @@ impl FloatExt for f64 {}
 impl FloatExt for float {}
 
 
-fn test_float_ext<T:FloatExt>(n: T) { println(fmt!("%?", n < n)) }
+fn test_float_ext<T:FloatExt>(n: T) { printfln!(n < n) }
 
 pub fn main() {
     test_float_ext(1f32);
diff --git a/src/test/run-pass/trait-inheritance-num3.rs b/src/test/run-pass/trait-inheritance-num3.rs
index e0285a7b59831..2d6b5e1132536 100644
--- a/src/test/run-pass/trait-inheritance-num3.rs
+++ b/src/test/run-pass/trait-inheritance-num3.rs
@@ -16,7 +16,7 @@ pub trait NumExt: Eq + Ord + Num + NumCast {}
 impl NumExt for f32 {}
 
 fn num_eq_one<T:NumExt>(n: T) {
-    println(fmt!("%?", n == NumCast::from(1)))
+    printfln!(n == NumCast::from(1))
 }
 
 pub fn main() {
diff --git a/src/test/run-pass/tuple-struct-construct.rs b/src/test/run-pass/tuple-struct-construct.rs
index 20be5df3242e7..9f1b930f16835 100644
--- a/src/test/run-pass/tuple-struct-construct.rs
+++ b/src/test/run-pass/tuple-struct-construct.rs
@@ -12,5 +12,5 @@ struct Foo(int, int);
 
 pub fn main() {
     let x = Foo(1, 2);
-    println(fmt!("%?", x));
+    printfln!(x);
 }
diff --git a/src/test/run-pass/tuple-struct-destructuring.rs b/src/test/run-pass/tuple-struct-destructuring.rs
index 4a1258264f8d1..a1b1f36dc4131 100644
--- a/src/test/run-pass/tuple-struct-destructuring.rs
+++ b/src/test/run-pass/tuple-struct-destructuring.rs
@@ -13,7 +13,7 @@ struct Foo(int, int);
 pub fn main() {
     let x = Foo(1, 2);
     let Foo(y, z) = x;
-    println(fmt!("%d %d", y, z));
+    printfln!("%d %d", y, z);
     assert_eq!(y, 1);
     assert_eq!(z, 2);
 }
diff --git a/src/test/run-pass/tuple-struct-matching.rs b/src/test/run-pass/tuple-struct-matching.rs
index 261b913b1d2c8..36467189bbd9b 100644
--- a/src/test/run-pass/tuple-struct-matching.rs
+++ b/src/test/run-pass/tuple-struct-matching.rs
@@ -16,7 +16,7 @@ pub fn main() {
         Foo(a, b) => {
             assert_eq!(a, 1);
             assert_eq!(b, 2);
-            println(fmt!("%d %d", a, b));
+            printfln!("%d %d", a, b);
         }
     }
 }
diff --git a/src/test/run-pass/vec-fixed-length.rs b/src/test/run-pass/vec-fixed-length.rs
index 56adc6d259881..e4c6bcf6791e2 100644
--- a/src/test/run-pass/vec-fixed-length.rs
+++ b/src/test/run-pass/vec-fixed-length.rs
@@ -10,5 +10,5 @@
 
 pub fn main() {
     let x: [int, ..4] = [1, 2, 3, 4];
-    println(fmt!("%d", x[0]));
+    printfln!("%d", x[0]);
 }
diff --git a/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs b/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
index aae287deb8a1e..08b62cce71562 100644
--- a/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
+++ b/src/test/run-pass/vec-matching-legal-tail-element-borrow.rs
@@ -5,6 +5,6 @@ pub fn main() {
             [1, ..ref tail] => &tail[0],
             _ => ::std::util::unreachable()
         };
-        println(fmt!("%d", *el));
+        printfln!("%d", *el);
     }
 }