diff --git a/slog-handler-guide/indenthandler1/indent_handler_test.go b/slog-handler-guide/indenthandler1/indent_handler_test.go
index b295fa66..3165c999 100644
--- a/slog-handler-guide/indenthandler1/indent_handler_test.go
+++ b/slog-handler-guide/indenthandler1/indent_handler_test.go
@@ -15,7 +15,7 @@ func Test(t *testing.T) {
 	l := slog.New(New(&buf, nil))
 	l.Info("hello", "a", 1, "b", true, "c", 3.14, slog.Group("g", "h", 1, "i", 2), "d", "NO")
 	got := buf.String()
-	wantre := `time: [-0-9T:.]+Z?
+	wantre := `time: [-0-9T:.]+(Z|[+-][0-9]{2}:[0-9]{2})?
 level: INFO
 source: ".*/indent_handler_test.go:\d+"
 msg: "hello"
diff --git a/slog-handler-guide/indenthandler2/indent_handler_test.go b/slog-handler-guide/indenthandler2/indent_handler_test.go
index 40633525..d3f8bbaa 100644
--- a/slog-handler-guide/indenthandler2/indent_handler_test.go
+++ b/slog-handler-guide/indenthandler2/indent_handler_test.go
@@ -32,7 +32,7 @@ func Test(t *testing.T) {
 	l := slog.New(New(&buf, nil))
 	l.Info("hello", "a", 1, "b", true, "c", 3.14, slog.Group("g", "h", 1, "i", 2), "d", "NO")
 	got := buf.String()
-	wantre := `time: [-0-9T:.]+Z?
+	wantre := `time: [-0-9T:.]+(Z|[+-][0-9]{2}:[0-9]{2})?
 level: INFO
 source: ".*/indent_handler_test.go:\d+"
 msg: "hello"
diff --git a/slog-handler-guide/indenthandler3/indent_handler_test.go b/slog-handler-guide/indenthandler3/indent_handler_test.go
index 8f6e99ca..461b5a8f 100644
--- a/slog-handler-guide/indenthandler3/indent_handler_test.go
+++ b/slog-handler-guide/indenthandler3/indent_handler_test.go
@@ -31,7 +31,7 @@ func Test(t *testing.T) {
 	l := slog.New(New(&buf, nil))
 	l.Info("hello", "a", 1, "b", true, "c", 3.14, slog.Group("g", "h", 1, "i", 2), "d", "NO")
 	got := buf.String()
-	wantre := `time: [-0-9T:.]+Z?
+	wantre := `time: [-0-9T:.]+(Z|[+-][0-9]{2}:[0-9]{2})?
 level: INFO
 source: ".*/indent_handler_test.go:\d+"
 msg: "hello"
diff --git a/slog-handler-guide/indenthandler4/indent_handler_test.go b/slog-handler-guide/indenthandler4/indent_handler_test.go
index 8f6e99ca..461b5a8f 100644
--- a/slog-handler-guide/indenthandler4/indent_handler_test.go
+++ b/slog-handler-guide/indenthandler4/indent_handler_test.go
@@ -31,7 +31,7 @@ func Test(t *testing.T) {
 	l := slog.New(New(&buf, nil))
 	l.Info("hello", "a", 1, "b", true, "c", 3.14, slog.Group("g", "h", 1, "i", 2), "d", "NO")
 	got := buf.String()
-	wantre := `time: [-0-9T:.]+Z?
+	wantre := `time: [-0-9T:.]+(Z|[+-][0-9]{2}:[0-9]{2})?
 level: INFO
 source: ".*/indent_handler_test.go:\d+"
 msg: "hello"