diff --git a/src/cmd/compile/internal/types2/index.go b/src/cmd/compile/internal/types2/index.go
index 61009c121ec..37db50333ce 100644
--- a/src/cmd/compile/internal/types2/index.go
+++ b/src/cmd/compile/internal/types2/index.go
@@ -368,11 +368,7 @@ func (check *Checker) index(index syntax.Expr, max int64) (typ Type, val int64)
 	v, ok := constant.Int64Val(x.val)
 	assert(ok)
 	if max >= 0 && v >= max {
-		if check.conf.CompilerErrorMessages {
-			check.errorf(&x, invalidArg+"array index %s out of bounds [0:%d]", x.val.String(), max)
-		} else {
-			check.errorf(&x, invalidArg+"index %s is out of bounds", &x)
-		}
+		check.errorf(&x, invalidArg+"index %s out of bounds [0:%d]", x.val.String(), max)
 		return
 	}
 
diff --git a/src/go/types/index.go b/src/go/types/index.go
index 33075edaf14..670c95d6219 100644
--- a/src/go/types/index.go
+++ b/src/go/types/index.go
@@ -365,7 +365,7 @@ func (check *Checker) index(index ast.Expr, max int64) (typ Type, val int64) {
 	v, ok := constant.Int64Val(x.val)
 	assert(ok)
 	if max >= 0 && v >= max {
-		check.invalidArg(&x, _InvalidIndex, "index %s is out of bounds", &x)
+		check.invalidArg(&x, _InvalidIndex, "index %s out of bounds [0:%d]", x.val.String(), max)
 		return
 	}
 
diff --git a/test/fixedbugs/issue13365.go b/test/fixedbugs/issue13365.go
index b22fa0fb4e5..02c6e036984 100644
--- a/test/fixedbugs/issue13365.go
+++ b/test/fixedbugs/issue13365.go
@@ -16,7 +16,7 @@ func main() {
 	_ = [...]int{-1: 0} // ERROR "index must be non\-negative integer constant|index expression is negative|must not be negative"
 
 	_ = []int{100: 0}
-	_ = [10]int{100: 0} // ERROR "array index 100 out of bounds|out of range"
+	_ = [10]int{100: 0} // ERROR "index 100 out of bounds|out of range"
 	_ = [...]int{100: 0}
 
 	_ = []int{t}    // ERROR "cannot use .* as (type )?int( in slice literal)?|incompatible type"