diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 90c7a5d3f39fa37f76005f354976e8f9c8c1270e..37b60b80a7624566d9ecefdd04c0658134bd654d 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -429,7 +429,8 @@ int fw_env_write(char *name, char *value)
  */
 int fw_setenv(int argc, char *argv[])
 {
-	int i, len;
+	int i;
+	size_t len;
 	char *name;
 	char *value = NULL;