diff --git a/tccpp.c b/tccpp.c
index 2609ad7..f4b7b1a 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -255,9 +255,15 @@ ST_FUNC char *get_tok_str(int v, CValue *cv)
     static char buf[STRING_MAX_SIZE + 1];
     static CString cstr_buf;
     CString *cstr;
+    CValue cval;
     char *p;
     int i, len;
 
+    if (!cv) {
+        cval.ull = 0;
+        cv = &cval;
+    }
+
     /* NOTE: to go faster, we give a fixed buffer for small strings */
     cstr_reset(&cstr_buf);
     cstr_buf.data = buf;