diff --git a/WORKSPACE b/WORKSPACE
index d3121d8743..77205b7718 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -358,7 +358,7 @@ yarn_install(
 ##############################################################################
 
 # PHP micro-generator
-_gapic_generator_php_version = "1.6.3"
+_gapic_generator_php_version = "1.6.4"
 
 http_archive(
     name = "gapic_generator_php",