diff --git a/api/fuchsia.txt b/api/fuchsia.txt
index 85c8941..b4f7d72 100644
--- a/api/fuchsia.txt
+++ b/api/fuchsia.txt
@@ -1087,7 +1087,6 @@
 pkg syscall/zx/fidl, const Invalid ErrorCode
 pkg syscall/zx/fidl, const ProtocolRights = 61454
 pkg syscall/zx/fidl, const ProtocolRights zx.Rights
-pkg syscall/zx/fidl, func AllowV2WireFormatDecoding()
 pkg syscall/zx/fidl, func CreateLazyMarshaler(interface{}) Marshaler
 pkg syscall/zx/fidl, func CreateMarshaler(interface{}) (Marshaler, error)
 pkg syscall/zx/fidl, func GetMarshalerContext(context.Context) (MarshalerContext, bool)
diff --git a/src/syscall/zx/fidl/ctx_and_header.go b/src/syscall/zx/fidl/ctx_and_header.go
index 78e9096..bac8a2f 100644
--- a/src/syscall/zx/fidl/ctx_and_header.go
+++ b/src/syscall/zx/fidl/ctx_and_header.go
@@ -4,13 +4,6 @@
 
 package fidl
 
-var allowV2WireFormatDecoding bool
-
-// Enable V2 wire format decoding for this process.
-func AllowV2WireFormatDecoding() {
-	allowV2WireFormatDecoding = true
-}
-
 const FidlWireFormatMagicNumberInitial = 0x01
 
 const FidlV2WireFormatFlagMask = 0x02
@@ -24,7 +17,7 @@
 }
 
 func (ctx MarshalerContext) isV2WireFormatDecodingEnabled() bool {
-	return allowV2WireFormatDecoding && ctx.UseV2WireFormat
+	return ctx.UseV2WireFormat
 }
 
 // newCtx returns the default context.
diff --git a/src/syscall/zx/fidl/fidl_test/testutil_test.go b/src/syscall/zx/fidl/fidl_test/testutil_test.go
index e2f1edd..4a44f58 100644
--- a/src/syscall/zx/fidl/fidl_test/testutil_test.go
+++ b/src/syscall/zx/fidl/fidl_test/testutil_test.go
@@ -14,10 +14,6 @@
 	"syscall/zx/fidl"
 )
 
-func init() {
-	fidl.AllowV2WireFormatDecoding()
-}
-
 func makeDefault(typ reflect.Type) fidl.Message {
 	if typ.Kind() != reflect.Ptr || typ.Elem().Kind() != reflect.Struct {
 		panic(fmt.Sprintf("expecting *struct, actual %s", typ))