diff --git a/platform/src/ssl_utils.cc b/platform/src/ssl_utils.cc
index 0e2c306..dd25a79 100644
--- a/platform/src/ssl_utils.cc
+++ b/platform/src/ssl_utils.cc
@@ -1910,7 +1910,10 @@ static char* parse_cipher_suites(struct cipher_suite* _cipher_suite_list, int n,
 		pos += 2;
 	}
 	int len = strnlen(cipher_suites_str, TFE_STRING_MAX);
-	cipher_suites_str[len-1] = '\0';
+	if(len > 0)
+	{
+		cipher_suites_str[len-1] = '\0';
+	}
 	if(pos != buff_len)
 	{
 		*result = CHELLO_PARSE_INVALID_FORMAT;