diff --git a/src/goodbyedpi.c b/src/goodbyedpi.c
index 8fa7313..cfa2ac8 100644
--- a/src/goodbyedpi.c
+++ b/src/goodbyedpi.c
@@ -415,7 +415,7 @@ static int extract_sni(const char *pktdata, unsigned int pktlen,
                 }
                 /* Validate that hostname has only ascii lowercase characters */
                 for (int i=0; i<hnlen; i++) {
-                    if (!( (hnaddr[i] >= '1' && hnaddr[i] <= '9') ||
+                    if (!( (hnaddr[i] >= '0' && hnaddr[i] <= '9') ||
                          (hnaddr[i] >= 'a' && hnaddr[i] <= 'z') ||
                          hnaddr[i] == '.' || hnaddr[i] == '-'))
                     {