diff --git a/builtins/util.m4 b/builtins/util.m4
index a97336a7..dbe073fb 100644
--- a/builtins/util.m4
+++ b/builtins/util.m4
@@ -2499,14 +2499,14 @@ define void @__memset64(i8 * %dst, i8 %val, i64 %len) alwaysinline {
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; assert
 
-declare i32 @printf(i8*, ...)
+declare i32 @puts(i8*)
 declare void @abort() noreturn
 
 define void @__do_assert_uniform(i8 *%str, i1 %test, <WIDTH x MASK> %mask) {
   br i1 %test, label %ok, label %fail
 
 fail:
-  %call = call i32 (i8*, ...)* @printf(i8* %str)
+  %call = call i32 @puts(i8* %str)
   call void @abort() noreturn
   unreachable
 
@@ -2525,7 +2525,7 @@ define void @__do_assert_varying(i8 *%str, <WIDTH x MASK> %test,
   br i1 %all_ok, label %ok, label %fail
 
 fail:
-  %call = call i32 (i8*, ...)* @printf(i8* %str)
+  %call = call i32 @puts(i8* %str)
   call void @abort() noreturn
   unreachable
 
diff --git a/stmt.cpp b/stmt.cpp
index 94a6b857..b663c661 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -3142,14 +3142,14 @@ AssertStmt::EmitCode(FunctionEmitContext *ctx) const {
     bool isUniform = type->IsUniformType();
 
     // The actual functionality to do the check and then handle falure is
-    // done via a builtin written in bitcode in builtins.m4.
+    // done via a builtin written in bitcode in builtins/util.m4.
     llvm::Function *assertFunc = 
         isUniform ? m->module->getFunction("__do_assert_uniform") :
                     m->module->getFunction("__do_assert_varying");
     AssertPos(pos, assertFunc != NULL);
 
     char *errorString;
-    if (asprintf(&errorString, "%s:%d:%d: Assertion failed: %s\n", 
+    if (asprintf(&errorString, "%s:%d:%d: Assertion failed: %s", 
                  pos.name, pos.first_line, pos.first_column, 
                  message.c_str()) == -1) {
         Error(pos, "Fatal error when generating assert string: asprintf() "