diff --git a/src/core/misc.c b/src/core/misc.c
index ed88be1c..b1e2521a 100644
--- a/src/core/misc.c
+++ b/src/core/misc.c
@@ -421,6 +421,9 @@ int is_numeric(const char *str, char end_char)
 {
 	g_return_val_if_fail(str != NULL, FALSE);
 
+	if (*str == '\0' || *str == end_char)
+		return FALSE;
+
 	while (*str != '\0' && *str != end_char) {
 		if (!isdigit(*str)) return FALSE;
 		str++;