diff --git a/src/parser.ts b/src/parser.ts
index 55ca4982..47d5aab9 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -18,7 +18,8 @@ import {
   Token,
   Range,
   CommentHandler,
-  IdentifierHandling
+  IdentifierHandling,
+  isIllegalVariableIdentifier
 } from "./tokenizer";
 
 import {
@@ -815,6 +816,12 @@ export class Parser extends DiagnosticEmitter {
       return null;
     }
     var identifier = Node.createIdentifierExpression(tn.readIdentifier(), tn.range());
+    if (isIllegalVariableIdentifier(identifier.text)) {
+      this.error(
+        DiagnosticCode.Identifier_expected,
+        identifier.range
+      );
+    }
     var flags = parentFlags;
     if (tn.skip(Token.EXCLAMATION)) {
       flags |= CommonFlags.DEFINITE_ASSIGNMENT;
@@ -1780,10 +1787,17 @@ export class Parser extends DiagnosticEmitter {
 
     var readonlyStart: i32 = 0;
     var readonlyEnd: i32 = 0;
-    if (tn.skip(Token.READONLY)) {
-      flags |= CommonFlags.READONLY;
-      readonlyStart = tn.tokenPos;
-      readonlyEnd = tn.pos;
+    if (tn.peek() == Token.READONLY) {
+      let state = tn.mark();
+      tn.next();
+      if (tn.peek() != Token.COLON) { // modifier
+        tn.discard(state);
+        flags |= CommonFlags.READONLY;
+        readonlyStart = tn.tokenPos;
+        readonlyEnd = tn.pos;
+      } else { // identifier
+        tn.reset(state);
+      }
     }
 
     // check if accessor: ('get' | 'set') ^\n Identifier
@@ -3426,7 +3440,9 @@ export class Parser extends DiagnosticEmitter {
         );
       }
       case Token.IDENTIFIER: {
-        let identifier = Node.createIdentifierExpression(tn.readIdentifier(), tn.range(startPos, tn.pos));
+        let identifierText = tn.readIdentifier();
+        if (identifierText == "null") return Node.createNullExpression(tn.range()); // special
+        let identifier = Node.createIdentifierExpression(identifierText, tn.range(startPos, tn.pos));
         if (tn.peek(true) == Token.EQUALS_GREATERTHAN && !tn.nextTokenOnNewLine) {
           return this.parseFunctionExpressionCommon(
             tn,
diff --git a/src/tokenizer.ts b/src/tokenizer.ts
index d9c38b82..e55acd1e 100644
--- a/src/tokenizer.ts
+++ b/src/tokenizer.ts
@@ -355,6 +355,7 @@ export function tokenIsAlsoIdentifier(token: Token): bool {
     case Token.KEYOF:
     case Token.MODULE:
     case Token.NAMESPACE:
+    case Token.NULL:
     case Token.READONLY:
     case Token.SET:
     case Token.TYPE:
@@ -363,6 +364,18 @@ export function tokenIsAlsoIdentifier(token: Token): bool {
   }
 }
 
+export function isIllegalVariableIdentifier(name: string): bool {
+  assert(name.length);
+  switch (name.charCodeAt(0)) {
+    case CharCode.d: return name == "delete";
+    case CharCode.f: return name == "for";
+    case CharCode.i: return name == "instanceof";
+    case CharCode.n: return name == "null";
+    case CharCode.v: return name == "void";
+  }
+  return false;
+}
+
 export function operatorTokenToString(token: Token): string {
   switch (token) {
     case Token.DELETE: return "delete";
diff --git a/tests/compiler/call-super.untouched.wat b/tests/compiler/call-super.untouched.wat
index d0365d64..866c9146 100644
--- a/tests/compiler/call-super.untouched.wat
+++ b/tests/compiler/call-super.untouched.wat
@@ -338,8 +338,6 @@
   local.get $0
  )
  (func $call-super/F#constructor (; 11 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
-  (local $1 i32)
-  (local $2 i32)
   local.get $0
   i32.eqz
   if
@@ -351,16 +349,11 @@
   end
   local.get $0
   call $call-super/E#constructor
-  local.tee $1
   local.set $0
   local.get $0
   i32.const 2
   i32.store offset=4
   local.get $0
-  local.set $2
-  local.get $1
-  call $~lib/rt/stub/__release
-  local.get $2
  )
  (func $call-super/test3 (; 12 ;) (type $FUNCSIG$v)
   (local $0 i32)
@@ -412,8 +405,6 @@
   local.get $0
  )
  (func $call-super/H#constructor (; 14 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
-  (local $1 i32)
-  (local $2 i32)
   local.get $0
   i32.eqz
   if
@@ -425,16 +416,11 @@
   end
   local.get $0
   call $call-super/G#constructor
-  local.tee $1
   local.set $0
   local.get $0
   i32.const 2
   i32.store offset=4
   local.get $0
-  local.set $2
-  local.get $1
-  call $~lib/rt/stub/__release
-  local.get $2
  )
  (func $call-super/test4 (; 15 ;) (type $FUNCSIG$v)
   (local $0 i32)
@@ -486,8 +472,6 @@
   local.get $0
  )
  (func $call-super/J#constructor (; 17 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
-  (local $1 i32)
-  (local $2 i32)
   local.get $0
   i32.eqz
   if
@@ -499,16 +483,11 @@
   end
   local.get $0
   call $call-super/I#constructor
-  local.tee $1
   local.set $0
   local.get $0
   i32.const 2
   i32.store offset=4
   local.get $0
-  local.set $2
-  local.get $1
-  call $~lib/rt/stub/__release
-  local.get $2
  )
  (func $call-super/test5 (; 18 ;) (type $FUNCSIG$v)
   (local $0 i32)
diff --git a/tests/compiler/rt/instanceof.untouched.wat b/tests/compiler/rt/instanceof.untouched.wat
index acaa8057..7816af7b 100644
--- a/tests/compiler/rt/instanceof.untouched.wat
+++ b/tests/compiler/rt/instanceof.untouched.wat
@@ -1,7 +1,6 @@
 (module
  (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
  (type $FUNCSIG$ii (func (param i32) (result i32)))
- (type $FUNCSIG$vi (func (param i32)))
  (type $FUNCSIG$viiii (func (param i32 i32 i32 i32)))
  (type $FUNCSIG$v (func))
  (import "env" "abort" (func $~lib/builtins/abort (param i32 i32 i32 i32)))
@@ -133,12 +132,7 @@
   end
   local.get $0
  )
- (func $~lib/rt/stub/__release (; 4 ;) (type $FUNCSIG$vi) (param $0 i32)
-  nop
- )
- (func $rt/instanceof/Cat#constructor (; 5 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
-  (local $1 i32)
-  (local $2 i32)
+ (func $rt/instanceof/Cat#constructor (; 4 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
   local.get $0
   i32.eqz
   if
@@ -150,17 +144,10 @@
   end
   local.get $0
   call $rt/instanceof/Animal#constructor
-  local.tee $1
   local.set $0
   local.get $0
-  local.set $2
-  local.get $1
-  call $~lib/rt/stub/__release
-  local.get $2
  )
- (func $rt/instanceof/BlackCat#constructor (; 6 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
-  (local $1 i32)
-  (local $2 i32)
+ (func $rt/instanceof/BlackCat#constructor (; 5 ;) (type $FUNCSIG$ii) (param $0 i32) (result i32)
   local.get $0
   i32.eqz
   if
@@ -172,15 +159,10 @@
   end
   local.get $0
   call $rt/instanceof/Cat#constructor
-  local.tee $1
   local.set $0
   local.get $0
-  local.set $2
-  local.get $1
-  call $~lib/rt/stub/__release
-  local.get $2
  )
- (func $~lib/rt/__instanceof (; 7 ;) (type $FUNCSIG$iii) (param $0 i32) (param $1 i32) (result i32)
+ (func $~lib/rt/__instanceof (; 6 ;) (type $FUNCSIG$iii) (param $0 i32) (param $1 i32) (result i32)
   (local $2 i32)
   (local $3 i32)
   local.get $0
@@ -217,7 +199,7 @@
   end
   i32.const 0
  )
- (func $start:rt/instanceof (; 8 ;) (type $FUNCSIG$v)
+ (func $start:rt/instanceof (; 7 ;) (type $FUNCSIG$v)
   (local $0 i32)
   global.get $~lib/heap/__heap_base
   i32.const 15
@@ -713,7 +695,7 @@
    unreachable
   end
  )
- (func $start (; 9 ;) (type $FUNCSIG$v)
+ (func $start (; 8 ;) (type $FUNCSIG$v)
   global.get $~lib/started
   if
    return
@@ -723,6 +705,6 @@
   end
   call $start:rt/instanceof
  )
- (func $null (; 10 ;) (type $FUNCSIG$v)
+ (func $null (; 9 ;) (type $FUNCSIG$v)
  )
 )
diff --git a/tests/parser/also-identifier.ts b/tests/parser/also-identifier.ts
new file mode 100644
index 00000000..39b5477b
--- /dev/null
+++ b/tests/parser/also-identifier.ts
@@ -0,0 +1,38 @@
+class Foo {
+  as: i32;
+  declare: i32;
+  delete: i32;
+  from: i32;
+  for: i32;
+  get: i32;
+  instanceof: i32;
+  is: i32;
+  keyof: i32;
+  module: i32;
+  namespace: i32;
+  null: i32;
+  readonly: i32;
+  set: i32;
+  type: i32;
+  void: i32;
+}
+
+var as: i32;
+var constructor: i32;
+var declare: i32;
+var from: i32;
+var get: i32;
+var is: i32;
+var keyof: i32;
+var module: i32;
+var namespace: i32;
+var readonly: i32;
+var set: i32;
+
+// -- illegal --
+// var delete: i32;
+// var for: i32;
+// var instanceof: i32;
+// var null: i32;
+// var type: i32;
+// var void: i32;
diff --git a/tests/parser/also-identifier.ts.fixture.ts b/tests/parser/also-identifier.ts.fixture.ts
new file mode 100644
index 00000000..8de8b517
--- /dev/null
+++ b/tests/parser/also-identifier.ts.fixture.ts
@@ -0,0 +1,29 @@
+class Foo {
+  as: i32;
+  declare: i32;
+  delete: i32;
+  from: i32;
+  for: i32;
+  get: i32;
+  instanceof: i32;
+  is: i32;
+  keyof: i32;
+  module: i32;
+  namespace: i32;
+  null: i32;
+  readonly: i32;
+  set: i32;
+  type: i32;
+  void: i32;
+}
+var as: i32;
+var constructor: i32;
+var declare: i32;
+var from: i32;
+var get: i32;
+var is: i32;
+var keyof: i32;
+var module: i32;
+var namespace: i32;
+var readonly: i32;
+var set: i32;