diff --git a/tools/webassembly.py b/tools/webassembly.py
index f8c9a3be38841..2aa782688b045 100644
--- a/tools/webassembly.py
+++ b/tools/webassembly.py
@@ -165,7 +165,6 @@ class DylinkType(IntEnum):
 class TargetFeaturePrefix(IntEnum):
   USED = 0x2b
   DISALLOWED = 0x2d
-  REQUIRED = 0x3d
 
 
 class InvalidWasmError(BaseException):