diff --git a/src/cmd/gc/mparith1.c b/src/cmd/gc/mparith1.c
index e25044a8be..41412c416d 100644
--- a/src/cmd/gc/mparith1.c
+++ b/src/cmd/gc/mparith1.c
@@ -65,7 +65,7 @@ mpcmpfltc(Mpflt *b, double c)
 	Mpflt a;
 
 	mpmovecflt(&a, c);
-	return mpcmpfltflt(&a, b);
+	return mpcmpfltflt(b, &a);
 }
 
 void
diff --git a/test/fixedbugs/issue6964.go b/test/fixedbugs/issue6964.go
new file mode 100644
index 0000000000..821735c082
--- /dev/null
+++ b/test/fixedbugs/issue6964.go
@@ -0,0 +1,11 @@
+// errorcheck
+
+// Copyright 2013 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 main
+
+func main() {
+	_ = string(-4 + 2i + 2) // ERROR "-4\+2i"
+}