diff --git a/tccasm.c b/tccasm.c
index b494398..9dcab1c 100644
--- a/tccasm.c
+++ b/tccasm.c
@@ -42,7 +42,7 @@ static void asm_expr_unary(TCCState *s1, ExprValue *pe)
 {
     Sym *sym;
     int op, label;
-    long n;
+    unsigned long n;
     const char *p;
 
     switch(tok) {