diff --git a/config/compiler/BUILD.gn b/config/compiler/BUILD.gn
index 4a7faee56..a4def5a76 100644
--- a/config/compiler/BUILD.gn
+++ b/config/compiler/BUILD.gn
@@ -1064,6 +1064,11 @@ config("default_warnings") {
       # also contain a default: branch. Chrome is full of that.
       "-Wno-covered-switch-default",
 
+      # Clang considers the `register` keyword as deprecated, but e.g.
+      # code generated by flex (used in angle) contains that keyword.
+      # http://crbug.com/255186
+      "-Wno-deprecated-register",
+
       # TODO(thakis): This used to be implied by -Wno-unused-function,
       # which we no longer use. Check if it makes sense to remove
       # this as well. http://crbug.com/316352