diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go
index 6fe249f171a30..03c52a078ce21 100644
--- a/src/cmd/compile/internal/gc/const.go
+++ b/src/cmd/compile/internal/gc/const.go
@@ -259,7 +259,6 @@ func convlit1(np **Node, t *Type, explicit bool) {
 				n.SetVal(toint(n.Val()))
 				fallthrough
 
-				// flowthrough
 			case CTINT:
 				overflow(n.Val(), t)
 			}
@@ -272,7 +271,6 @@ func convlit1(np **Node, t *Type, explicit bool) {
 				n.SetVal(toflt(n.Val()))
 				fallthrough
 
-				// flowthrough
 			case CTFLT:
 				n.SetVal(Val{truncfltlit(n.Val().U.(*Mpflt), t)})
 			}
@@ -283,6 +281,7 @@ func convlit1(np **Node, t *Type, explicit bool) {
 
 			case CTFLT, CTINT, CTRUNE:
 				n.SetVal(tocplx(n.Val()))
+				fallthrough
 
 			case CTCPLX:
 				overflow(n.Val(), t)
diff --git a/test/fixedbugs/issue11590.go b/test/fixedbugs/issue11590.go
new file mode 100644
index 0000000000000..9776704b2a496
--- /dev/null
+++ b/test/fixedbugs/issue11590.go
@@ -0,0 +1,11 @@
+// errorcheck
+
+// Copyright 2015 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+var _ = int8(4) * 300         // ERROR "constant overflows int8"
+var _ = complex64(1) * 1e200  // ERROR "constant overflows complex64"
+var _ = complex128(1) * 1e500 // ERROR "constant overflows complex128"