diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index cd8a2f0..edd3f39 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -348,7 +348,7 @@
 /*
  * e1 || e2 -> ?
  */
-struct expr *expr_join_or(struct expr *e1, struct expr *e2)
+static struct expr *expr_join_or(struct expr *e1, struct expr *e2)
 {
 	struct expr *tmp;
 	struct symbol *sym1, *sym2;
@@ -412,7 +412,7 @@
 	return NULL;
 }
 
-struct expr *expr_join_and(struct expr *e1, struct expr *e2)
+static struct expr *expr_join_and(struct expr *e1, struct expr *e2)
 {
 	struct expr *tmp;
 	struct symbol *sym1, *sym2;