diff --git a/src/runtime/panic.go b/src/runtime/panic.go
index eb49c12c0..12a139967 100644
--- a/src/runtime/panic.go
+++ b/src/runtime/panic.go
@@ -1,5 +1,6 @@
 package runtime
 
+// Builtin function panic(msg), used as a compiler intrinsic.
 func _panic(message interface{}) {
 	printstring("panic: ")
 	printitf(message)
@@ -7,28 +8,30 @@ func _panic(message interface{}) {
 	abort()
 }
 
+// Cause a runtime panic, which is (currently) always a string.
+func runtimePanic(msg string) {
+	printstring("panic: runtime error: ")
+	println(msg)
+	abort()
+}
+
 // Check for bounds in *ssa.Index, *ssa.IndexAddr and *ssa.Lookup.
 func lookupBoundsCheck(length, index int) {
 	if index < 0 || index >= length {
-		// printstring() here is safe as this function is excluded from bounds
-		// checking.
-		printstring("panic: runtime error: index out of range\n")
-		abort()
+		runtimePanic("index out of range")
 	}
 }
 
 // Check for bounds in *ssa.Slice.
 func sliceBoundsCheck(length, low, high uint) {
 	if !(0 <= low && low <= high && high <= length) {
-		printstring("panic: runtime error: slice out of range\n")
-		abort()
+		runtimePanic("slice out of range")
 	}
 }
 
 // Check for bounds in *ssa.MakeSlice.
 func sliceBoundsCheckMake(length, capacity uint) {
 	if !(0 <= length && length <= capacity) {
-		printstring("panic: runtime error: slice size out of range\n")
-		abort()
+		runtimePanic("slice size out of range")
 	}
 }
diff --git a/src/runtime/runtime_unix.go b/src/runtime/runtime_unix.go
index 2c072022d..fb59175c9 100644
--- a/src/runtime/runtime_unix.go
+++ b/src/runtime/runtime_unix.go
@@ -48,7 +48,7 @@ func abort() {
 func alloc(size uintptr) unsafe.Pointer {
 	buf := _Cfunc_calloc(1, size)
 	if buf == nil {
-		panic("cannot allocate memory")
+		runtimePanic("cannot allocate memory")
 	}
 	return buf
 }