diff --git a/lib/std/heap.zig b/lib/std/heap.zig
index 3e74db386e94..50a943c4513c 100644
--- a/lib/std/heap.zig
+++ b/lib/std/heap.zig
@@ -736,7 +736,7 @@ test "WasmPageAllocator internals" {
     if (comptime std.Target.current.isWasm()) {
         const conventional_memsize = WasmPageAllocator.conventional.totalPages() * mem.page_size;
         const initial = try page_allocator.alloc(u8, mem.page_size);
-        std.debug.assert(@ptrToInt(initial.ptr) < conventional_memsize); // If this isn't conventional, the rest of these tests don't make sense. Also we have a serious memory leak in the test suite.
+        testing.expect(@ptrToInt(initial.ptr) < conventional_memsize); // If this isn't conventional, the rest of these tests don't make sense. Also we have a serious memory leak in the test suite.
 
         var inplace = try page_allocator.realloc(initial, 1);
         testing.expectEqual(initial.ptr, inplace.ptr);
diff --git a/lib/std/heap/logging_allocator.zig b/lib/std/heap/logging_allocator.zig
index 0e3e460b8937..f4e0ada76411 100644
--- a/lib/std/heap/logging_allocator.zig
+++ b/lib/std/heap/logging_allocator.zig
@@ -93,7 +93,7 @@ test "LoggingAllocator" {
 
     var a = try allocator.alloc(u8, 10);
     a = allocator.shrink(a, 5);
-    std.debug.assert(a.len == 5);
+    std.testing.expect(a.len == 5);
     std.testing.expectError(error.OutOfMemory, allocator.resize(a, 20));
     allocator.free(a);
 
diff --git a/lib/std/io/test.zig b/lib/std/io/test.zig
index ad519a91993e..584369966b43 100644
--- a/lib/std/io/test.zig
+++ b/lib/std/io/test.zig
@@ -40,11 +40,7 @@ test "write a file, read it, then delete it" {
 
     {
         // Make sure the exclusive flag is honored.
-        if (tmp.dir.createFile(tmp_file_name, .{ .exclusive = true })) |file| {
-            unreachable;
-        } else |err| {
-            std.debug.assert(err == File.OpenError.PathAlreadyExists);
-        }
+        expectError(File.OpenError.PathAlreadyExists, tmp.dir.createFile(tmp_file_name, .{ .exclusive = true }));
     }
 
     {
diff --git a/lib/std/math/exp.zig b/lib/std/math/exp.zig
index 35d26f2a5054..87e1031a24c2 100644
--- a/lib/std/math/exp.zig
+++ b/lib/std/math/exp.zig
@@ -11,8 +11,7 @@
 
 const std = @import("../std.zig");
 const math = std.math;
-const assert = std.debug.assert;
-const builtin = @import("builtin");
+const expect = std.testing.expect;
 
 /// Returns e raised to the power of x (e^x).
 ///
@@ -188,36 +187,36 @@ fn exp64(x_: f64) f64 {
 }
 
 test "math.exp" {
-    assert(exp(@as(f32, 0.0)) == exp32(0.0));
-    assert(exp(@as(f64, 0.0)) == exp64(0.0));
+    expect(exp(@as(f32, 0.0)) == exp32(0.0));
+    expect(exp(@as(f64, 0.0)) == exp64(0.0));
 }
 
 test "math.exp32" {
     const epsilon = 0.000001;
 
-    assert(exp32(0.0) == 1.0);
-    assert(math.approxEqAbs(f32, exp32(0.0), 1.0, epsilon));
-    assert(math.approxEqAbs(f32, exp32(0.2), 1.221403, epsilon));
-    assert(math.approxEqAbs(f32, exp32(0.8923), 2.440737, epsilon));
-    assert(math.approxEqAbs(f32, exp32(1.5), 4.481689, epsilon));
+    expect(exp32(0.0) == 1.0);
+    expect(math.approxEqAbs(f32, exp32(0.0), 1.0, epsilon));
+    expect(math.approxEqAbs(f32, exp32(0.2), 1.221403, epsilon));
+    expect(math.approxEqAbs(f32, exp32(0.8923), 2.440737, epsilon));
+    expect(math.approxEqAbs(f32, exp32(1.5), 4.481689, epsilon));
 }
 
 test "math.exp64" {
     const epsilon = 0.000001;
 
-    assert(exp64(0.0) == 1.0);
-    assert(math.approxEqAbs(f64, exp64(0.0), 1.0, epsilon));
-    assert(math.approxEqAbs(f64, exp64(0.2), 1.221403, epsilon));
-    assert(math.approxEqAbs(f64, exp64(0.8923), 2.440737, epsilon));
-    assert(math.approxEqAbs(f64, exp64(1.5), 4.481689, epsilon));
+    expect(exp64(0.0) == 1.0);
+    expect(math.approxEqAbs(f64, exp64(0.0), 1.0, epsilon));
+    expect(math.approxEqAbs(f64, exp64(0.2), 1.221403, epsilon));
+    expect(math.approxEqAbs(f64, exp64(0.8923), 2.440737, epsilon));
+    expect(math.approxEqAbs(f64, exp64(1.5), 4.481689, epsilon));
 }
 
 test "math.exp32.special" {
-    assert(math.isPositiveInf(exp32(math.inf(f32))));
-    assert(math.isNan(exp32(math.nan(f32))));
+    expect(math.isPositiveInf(exp32(math.inf(f32))));
+    expect(math.isNan(exp32(math.nan(f32))));
 }
 
 test "math.exp64.special" {
-    assert(math.isPositiveInf(exp64(math.inf(f64))));
-    assert(math.isNan(exp64(math.nan(f64))));
+    expect(math.isPositiveInf(exp64(math.inf(f64))));
+    expect(math.isNan(exp64(math.nan(f64))));
 }
diff --git a/lib/std/rand.zig b/lib/std/rand.zig
index 2c390ff41af0..61aa2dac31fd 100644
--- a/lib/std/rand.zig
+++ b/lib/std/rand.zig
@@ -1152,7 +1152,7 @@ test "CSPRNG" {
     const a = csprng.random.int(u64);
     const b = csprng.random.int(u64);
     const c = csprng.random.int(u64);
-    assert(a ^ b ^ c != 0);
+    expect(a ^ b ^ c != 0);
 }
 
 test "" {
diff --git a/src/libc_installation.zig b/src/libc_installation.zig
index b016589f4d43..7dd99273f11a 100644
--- a/src/libc_installation.zig
+++ b/src/libc_installation.zig
@@ -14,8 +14,6 @@ const log = std.log.scoped(.libc_installation);
 
 usingnamespace @import("windows_sdk.zig");
 
-// TODO https://github.com/ziglang/zig/issues/6345
-
 /// See the render function implementation for documentation of the fields.
 pub const LibCInstallation = struct {
     include_dir: ?[]const u8 = null,
diff --git a/test/stage1/behavior/bugs/421.zig b/test/stage1/behavior/bugs/421.zig
index a618876e004f..748cb3a62d8a 100644
--- a/test/stage1/behavior/bugs/421.zig
+++ b/test/stage1/behavior/bugs/421.zig
@@ -1,4 +1,4 @@
-const assert = @import("std").debug.assert;
+const expect = @import("std").testing.expect;
 
 test "bitCast to array" {
     comptime testBitCastArray();
@@ -6,7 +6,7 @@ test "bitCast to array" {
 }
 
 fn testBitCastArray() void {
-    assert(extractOne64(0x0123456789abcdef0123456789abcdef) == 0x0123456789abcdef);
+    expect(extractOne64(0x0123456789abcdef0123456789abcdef) == 0x0123456789abcdef);
 }
 
 fn extractOne64(a: u128) u64 {
diff --git a/test/standalone/use_alias/main.zig b/test/standalone/use_alias/main.zig
index 873393cef775..75a8b5e81a57 100644
--- a/test/standalone/use_alias/main.zig
+++ b/test/standalone/use_alias/main.zig
@@ -1,10 +1,10 @@
 const c = @import("c.zig");
-const assert = @import("std").debug.assert;
+const expect = @import("std").testing.expect;
 
 test "symbol exists" {
     var foo = c.Foo{
         .a = 1,
         .b = 1,
     };
-    assert(foo.a + foo.b == 2);
+    expect(foo.a + foo.b == 2);
 }