diff --git a/BUILD b/BUILD
index fdfa513c38..3b6fb2d57a 100644
--- a/BUILD
+++ b/BUILD
@@ -132,7 +132,6 @@ cc_library(
         "upb/collections/array.h",
         "upb/decode.h",
         "upb/encode.h",
-        "upb/extension_registry.h",
         "upb/mem/alloc.h",
         "upb/mem/arena.h",
         "upb/message/extension_internal.h",
diff --git a/upb/extension_registry.h b/upb/extension_registry.h
deleted file mode 100644
index 5a9564fb8b..0000000000
--- a/upb/extension_registry.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
- * Copyright (c) 2009-2021, Google LLC
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *     * Redistributions of source code must retain the above copyright
- *       notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above copyright
- *       notice, this list of conditions and the following disclaimer in the
- *       documentation and/or other materials provided with the distribution.
- *     * Neither the name of Google LLC nor the
- *       names of its contributors may be used to endorse or promote products
- *       derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL Google LLC BE LIABLE FOR ANY DIRECT,
- * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
- * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-// This header is deprecated, use upb/mini_table/extension_registry.h instead
-
-#ifndef UPB_EXTENSION_REGISTRY_H_
-#define UPB_EXTENSION_REGISTRY_H_
-
-#include "upb/mini_table/extension_registry.h"
-
-#endif /* UPB_EXTENSION_REGISTRY_H_ */
diff --git a/upb/generated_code_support.h b/upb/generated_code_support.h
index a328ccbfa0..1c93b40f85 100644
--- a/upb/generated_code_support.h
+++ b/upb/generated_code_support.h
@@ -33,7 +33,6 @@
 #include "upb/collections/array_internal.h"
 #include "upb/collections/map_gencode_util.h"
 #include "upb/collections/message_value.h"
-#include "upb/extension_registry.h"
 #include "upb/message/accessors.h"
 #include "upb/message/accessors_internal.h"
 #include "upb/message/extension_internal.h"
@@ -42,6 +41,7 @@
 #include "upb/mini_descriptor/decode.h"
 #include "upb/mini_table/enum.h"
 #include "upb/mini_table/extension.h"
+#include "upb/mini_table/extension_registry.h"
 #include "upb/mini_table/field.h"
 #include "upb/mini_table/file.h"
 #include "upb/mini_table/message.h"