diff --git a/scripts/kconfig/lexer.l b/scripts/kconfig/lexer.l
index c9df1c8..6354c90 100644
--- a/scripts/kconfig/lexer.l
+++ b/scripts/kconfig/lexer.l
@@ -378,7 +378,8 @@
 	if (!f && name != NULL && name[0] != '/') {
 		env = getenv(SRCTREE);
 		if (env) {
-			sprintf(fullname, "%s/%s", env, name);
+			snprintf(fullname, sizeof(fullname),
+				 "%s/%s", env, name);
 			f = fopen(fullname, "r");
 		}
 	}