diff --git a/src/cmd/gc/align.c b/src/cmd/gc/align.c
index 2440a4b3e27..d9d4df316fd 100644
--- a/src/cmd/gc/align.c
+++ b/src/cmd/gc/align.c
@@ -54,6 +54,8 @@ widstruct(Type *errtype, Type *t, vlong o, int flag)
 	for(f=t->type; f!=T; f=f->down) {
 		if(f->etype != TFIELD)
 			fatal("widstruct: not TFIELD: %lT", f);
+		if(f->type == T)
+			break;
 		dowidth(f->type);
 		if(f->type->align > maxalign)
 			maxalign = f->type->align;
diff --git a/test/typecheck.go b/test/typecheck.go
new file mode 100644
index 00000000000..239ceacc697
--- /dev/null
+++ b/test/typecheck.go
@@ -0,0 +1,18 @@
+// errorcheck
+
+// Verify that the Go compiler will not
+// die after running into an undefined
+// type in the argument list for a
+// function.
+// Does not compile.
+
+package main
+
+func mine(int b) int {	// ERROR "undefined.*b"
+	return b + 2	// ERROR "undefined.*b"
+}
+
+func main() {
+	mine()
+	c = mine()	// ERROR "undefined.*c" "cannot assign to c"
+}