diff --git a/lib/nodes.js b/lib/nodes.js
index 83be0b3df0..2ce6fdab3f 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -7,7 +7,12 @@
     child.prototype = new ctor;
     child.__super__ = parent.prototype;
     return child;
-  }, __bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; };
+  }, __bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; }, __indexOf = Array.prototype.indexOf || function(item) {
+    for (var i = 0, l = this.length; i < l; i++) {
+      if (this[i] === item) return i;
+    }
+    return -1;
+  };
   Scope = require('./scope').Scope;
   _ref = require('./helpers'), compact = _ref.compact, flatten = _ref.flatten, extend = _ref.extend, merge = _ref.merge, del = _ref.del, starts = _ref.starts, ends = _ref.ends, last = _ref.last;
   exports.extend = extend;
@@ -1281,7 +1286,7 @@
     Assign.prototype.compileConditional = function(o) {
       var left, rite, _ref2;
       _ref2 = this.variable.cacheReference(o), left = _ref2[0], rite = _ref2[1];
-      return new Op(this.context.slice(0, -1), left, new Assign(rite, this.value, '=')).compile(o);
+      return new Op(this.context.slice(0, -1), left, new Assign(rite, this.value, '='), void 0, __indexOf.call(this.context, "?") >= 0).compile(o);
     };
     Assign.prototype.compileSplice = function(o) {
       var code, exclusive, from, fromDecl, fromRef, name, to, valDef, valRef, _ref2, _ref3, _ref4;
@@ -1579,8 +1584,9 @@
   exports.Op = Op = (function() {
     var CONVERSIONS, INVERSIONS;
     __extends(Op, Base);
-    function Op(op, first, second, flip) {
+    function Op(op, first, second, flip, isExistentialEquals) {
       var call;
+      this.isExistentialEquals = isExistentialEquals;
       if (op === 'in') {
         return new In(first, second);
       }
@@ -1693,9 +1699,15 @@
         fst = this.first;
         ref = fst;
       }
-      return new If(new Existence(fst), ref, {
-        type: 'if'
-      }).addElse(this.second).compile(o);
+      if (this.isExistentialEquals) {
+        return new If(new Existence(fst).invert(), this.second, {
+          type: 'if'
+        }).compile(o);
+      } else {
+        return new If(new Existence(fst), ref, {
+          type: 'if'
+        }).addElse(this.second).compile(o);
+      }
     };
     Op.prototype.compileUnary = function(o) {
       var op, parts;
@@ -1829,9 +1841,9 @@
     Existence.prototype.children = ['expression'];
     Existence.prototype.invert = NEGATE;
     Existence.prototype.compileNode = function(o) {
-      var code, sym;
+      var cmp, cnj, code, _ref2;
       code = this.expression.compile(o, LEVEL_OP);
-      code = IDENTIFIER.test(code) && !o.scope.check(code) ? this.negated ? "typeof " + code + " === \"undefined\" || " + code + " === null" : "typeof " + code + " !== \"undefined\" && " + code + " !== null" : (sym = this.negated ? '==' : '!=', "" + code + " " + sym + " null");
+      code = IDENTIFIER.test(code) && !o.scope.check(code) ? ((_ref2 = this.negated ? ['===', '||'] : ['!==', '&&'], cmp = _ref2[0], cnj = _ref2[1], _ref2), "typeof " + code + " " + cmp + " \"undefined\" " + cnj + " " + code + " " + cmp + " null") : "" + code + " " + (this.negated ? '==' : '!=') + " null";
       if (o.level <= LEVEL_COND) {
         return code;
       } else {
diff --git a/src/nodes.coffee b/src/nodes.coffee
index bd594e42df..7e6e2dbeea 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -1009,7 +1009,7 @@ exports.Assign = class Assign extends Base
   # more than once.
   compileConditional: (o) ->
     [left, rite] = @variable.cacheReference o
-    new Op(@context.slice(0, -1), left, new Assign(rite, @value, '=')).compile o
+    new Op(@context.slice(0, -1), left, new Assign(rite, @value, '='), undefined, "?" in @context ).compile o
 
   # Compile the assignment from an array splice literal, using JavaScript's
   # `Array#splice` method.
@@ -1218,7 +1218,10 @@ exports.While = class While extends Base
 # Simple Arithmetic and logical operations. Performs some conversion from
 # CoffeeScript operations into their JavaScript equivalents.
 exports.Op = class Op extends Base
-  constructor: (op, first, second, flip) ->
+
+
+
+  constructor: (op, first, second, flip, @isExistentialEquals ) ->
     return new In first, second if op is 'in'
     if op is 'do'
       call = new Call first, first.params or []
@@ -1313,7 +1316,10 @@ exports.Op = class Op extends Base
     else
       fst = @first
       ref = fst
-    new If(new Existence(fst), ref, type: 'if').addElse(@second).compile o
+    if @isExistentialEquals
+      new If(new Existence(fst).invert(), @second, type: 'if').compile o
+    else
+      new If(new Existence(fst), ref, type: 'if').addElse(@second).compile o
 
   # Compile a unary **Op**.
   compileUnary: (o) ->
@@ -1426,13 +1432,11 @@ exports.Existence = class Existence extends Base
   compileNode: (o) ->
     code = @expression.compile o, LEVEL_OP
     code = if IDENTIFIER.test(code) and not o.scope.check code
-      if @negated
-        "typeof #{code} === \"undefined\" || #{code} === null"
-      else
-        "typeof #{code} !== \"undefined\" && #{code} !== null"
+        [cmp, cnj] = if @negated then ['===', '||'] else ['!==', '&&']
+        "typeof #{code} #{cmp} \"undefined\" #{cnj} #{code} #{cmp} null"
     else
-      sym = if @negated then '==' else '!='
-      "#{code} #{sym} null"
+      # do not use strict equality here; it will break existing code
+      "#{code} #{if @negated then '==' else '!='} null"
     if o.level <= LEVEL_COND then code else "(#{code})"
 
 #### Parens
diff --git a/test/assignment.coffee b/test/assignment.coffee
index f9fbb5e038..0a4eddc757 100644
--- a/test/assignment.coffee
+++ b/test/assignment.coffee
@@ -268,3 +268,38 @@ test "existential assignment", ->
   eq nonce, c
   d ?= nonce
   eq nonce, d
+
+test "#1216 ?= compilation", ->
+  c = (s) -> CoffeeScript.compile( s, {bare:true} )
+
+  # ?= with locally scoped var defined
+  eq c('a = 0; a ?= b'),
+    '''var a;
+    a = 0;
+    if (a == null) {
+      a = b;
+    };'''
+
+  # ?= with locally scoped var not defined
+  eq c('a ?= b'),
+    '''if (typeof a === "undefined" || a === null) {
+      a = b;
+    };'''
+
+  # ? with locally scoped var defined
+  eq c('a = 0; return unless a?'),
+    '''
+    var a;
+    a = 0;
+    if (a == null) {
+      return;
+    }
+    '''
+
+  # ? with locally scoped var not defined
+  eq c('return unless a?'),
+    '''
+    if (typeof a === "undefined" || a === null) {
+      return;
+    }
+    '''