diff --git a/src/distroquery.c b/src/distroquery.c
index cd0fee2..808a09a 100644
--- a/src/distroquery.c
+++ b/src/distroquery.c
@@ -201,7 +201,7 @@ main(int argc, char *argv[])
      }
 
      data = getenv("QUERY_STRING");
-     if (strlen(data)) {
+     if (data && strlen(data)) {
         print_xml_reply(data);
         printf("</distroquery>\n");
         exit(0);