diff --git a/str.c b/str.c
index 41b27db..82b8ae4 100644
--- a/str.c
+++ b/str.c
@@ -113,7 +113,7 @@ str_strdup_trimmed(const struct mystr* p_str)
   for (h = 0; h < (int)str_getlen(p_str) && vsf_sysutil_isspace(p_trimmed[h]); h++) ;
   for (t = str_getlen(p_str) - 1; t >= 0 && vsf_sysutil_isspace(p_trimmed[t]); t--) ;
   newlen = t - h + 1;
-  return newlen ? vsf_sysutil_strndup(p_trimmed+h, (unsigned int)newlen) : 0L;
+  return (newlen > 0) ? vsf_sysutil_strndup(p_trimmed+h, (unsigned int)newlen) : 0L;
 }
 
 void