diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index a726fb41d16..87e01699335 100644
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -2033,7 +2033,7 @@ runtime·memorydump(void)
 void
 runtime·gchelper(void)
 {
-	int32 nproc;
+	uint32 nproc;
 
 	gchelperstart();