diff --git a/expect.changes b/expect.changes
index 75f6933..9b425d9 100644
--- a/expect.changes
+++ b/expect.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Fri Mar 21 12:23:29 UTC 2025 - Richard Biener <rguenther@suse.com>
+
+- Use -std=gnu89 to avoid the new C23 default of GCC 15, the codebase
+  is still using K&R C after all.
+
 -------------------------------------------------------------------
 Sun May 12 10:24:16 UTC 2024 - Marcus Meissner <meissner@suse.com>
 
diff --git a/expect.spec b/expect.spec
index faa5c43..c6493c7 100644
--- a/expect.spec
+++ b/expect.spec
@@ -1,7 +1,7 @@
 #
 # spec file for package expect
 #
-# Copyright (c) 2024 SUSE LLC
+# Copyright (c) 2025 SUSE LLC
 #
 # All modifications and additions to the file contributed by third parties
 # remain the property of their copyright owners, unless otherwise agreed
@@ -59,7 +59,7 @@ expect package loaded.
 %autopatch -p0
 
 %build
-export CFLAGS="%{optflags} -fPIC -pie"
+export CFLAGS="%{optflags} -fPIC -pie -std=gnu89"
 autoreconf
 %configure \
 	--with-tcl=%_libdir \