diff --git a/src/libbpf.c b/src/libbpf.c
index b791bd088bc22dc2f7d75129e21792a35f41c2be..d7e730ba0b62456f10e29aa6b0c47c72fee8c5a1 100644
--- a/src/libbpf.c
+++ b/src/libbpf.c
@@ -1900,7 +1900,7 @@ static int set_kcfg_value_str(struct extern_desc *ext, char *ext_val,
 	}
 
 	len = strlen(value);
-	if (value[len - 1] != '"') {
+	if (len < 2 || value[len - 1] != '"') {
 		pr_warn("extern (kcfg) '%s': invalid string config '%s'\n",
 			ext->name, value);
 		return -EINVAL;