diff --git a/expr.cpp b/expr.cpp
index c1e6092f..fb363c58 100644
--- a/expr.cpp
+++ b/expr.cpp
@@ -3409,7 +3409,9 @@ FunctionCallExpr::TypeCheck() {
         if (t == NULL)
             return NULL;
         argTypes.push_back(t);
-        argCouldBeNULL.push_back(lIsAllIntZeros(args->exprs[i]));
+
+        argCouldBeNULL.push_back(lIsAllIntZeros(args->exprs[i]) ||
+                       dynamic_cast<NullPointerExpr *>(args->exprs[i]) != NULL);
     }
 
     FunctionSymbolExpr *fse = dynamic_cast<FunctionSymbolExpr *>(func);
diff --git a/tests/ptr-null-func-arg.ispc b/tests/ptr-null-func-arg.ispc
new file mode 100644
index 00000000..fdd0cbab
--- /dev/null
+++ b/tests/ptr-null-func-arg.ispc
@@ -0,0 +1,14 @@
+
+export uniform int width() { return programCount; }
+
+bool bar(float * x) {
+    return (x != 0);
+}
+
+export void f_f(uniform float RET[], uniform float aFOO[]) {
+    RET[programIndex] = bar(NULL);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 0;
+}