diff --git a/src/modems/hayes.c b/src/modems/hayes.c
index 787705e..576034b 100644
--- a/src/modems/hayes.c
+++ b/src/modems/hayes.c
@@ -4278,10 +4278,14 @@ static int _is_ussd_code(char const * number)
 	if(number == NULL || number[0] != '*')
 		return 0;
 	for(number++; *number != '\0'; number++)
-		if((*number >= '0' && *number <= '9') || *number == '*')
+		if(*number == '#')
+		{
+			if(*(number + 1) == '\0')
+				return 1;
+			continue;
+		}
+		else if((*number >= '0' && *number <= '9') || *number == '*')
 			continue;
-		else if(*number == '#' && *(number + 1) == '\0')
-			return 1;
 		else
 			return 0;
 	return 0;
diff --git a/tests/ussd.c b/tests/ussd.c
index 84abd89..9c7786f 100644
--- a/tests/ussd.c
+++ b/tests/ussd.c
@@ -31,7 +31,7 @@ static int _ussd(void)
 {
 	int ret = 0;
 	const char * codes[] = { "*100#", "*109*72348937857623#" };
-	const char * notcodes[] = { "*#06#" };
+	const char * notcodes[] = { "*#06#0" };
 	size_t i;
 
 	for(i = 0; i < sizeof(codes) / sizeof(*codes); i++)