diff --git a/rest-api-spec/src/main/resources/rest-api-spec/test/cat.indices/10_basic.yml b/rest-api-spec/src/main/resources/rest-api-spec/test/cat.indices/10_basic.yml
index c7eddf42d1b03..e2ad41587f5e8 100644
--- a/rest-api-spec/src/main/resources/rest-api-spec/test/cat.indices/10_basic.yml
+++ b/rest-api-spec/src/main/resources/rest-api-spec/test/cat.indices/10_basic.yml
@@ -42,9 +42,9 @@
                /^(
                   index1                                                    \s+
                   (\d+)                                                     \s+
-                  (\d\d\d\d\-\d\d\-\d\dT\d\d:\d\d:\d\d.\d\d\dZ) \s+
+                  (\d\d\d\d\-\d\d\-\d\dT\d\d:\d\d:\d\d(.\d\d\d)?Z) \s+
                   (\d+)                                                     \s+
-                  (\d\d\d\d\-\d\d\-\d\dT\d\d:\d\d:\d\d.\d\d\dZ) \s*
+                  (\d\d\d\d\-\d\d\-\d\dT\d\d:\d\d:\d\d(.\d\d\d)?Z) \s*
                 )
                 $/
   - do: