diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 5ff643e60d09..6e4d417604fa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2074,7 +2074,7 @@ 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;