diff --git a/lib/nodes.js b/lib/nodes.js
index 8b12d940..346ddce5 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -1293,7 +1293,7 @@
         o.scope.find(first);
       }
       if (this.operator === '?=') {
-        return ("" + first + " = " + (ExistenceNode.compileTest(o, this.first)) + " ? " + firstVar + " : " + second);
+        return ("" + first + " = " + (ExistenceNode.compileTest(o, literal(firstVar))) + " ? " + firstVar + " : " + second);
       }
       return "" + first + " = " + firstVar + " " + (this.operator.substr(0, 2)) + " " + second;
     };
diff --git a/src/nodes.coffee b/src/nodes.coffee
index d702c9cf..04da956a 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -1112,7 +1112,7 @@ exports.OpNode = class OpNode extends BaseNode
     [first, firstVar] = @first.compileReference o, precompile: yes, assignment: yes
     second = @second.compile o
     o.scope.find(first) if first.match(IDENTIFIER)
-    return "#first = #{ ExistenceNode.compileTest(o, @first) } ? #firstVar : #second" if @operator is '?='
+    return "#first = #{ ExistenceNode.compileTest(o, literal(firstVar)) } ? #firstVar : #second" if @operator is '?='
     "#first = #firstVar #{ @operator.substr(0, 2) } #second"
 
   # If this is an existence operator, we delegate to `ExistenceNode.compileTest`
diff --git a/test/test_operations.coffee b/test/test_operations.coffee
index b99dd0ec..3151f3f2 100644
--- a/test/test_operations.coffee
+++ b/test/test_operations.coffee
@@ -82,15 +82,15 @@ ok two is 'two'
 
 
 # Compound assignment should be careful about caching variables.
-list = [0, 0, 5, 10]
+list = [0, null, 5, 10]
 count = 1
 key = ->
   count += 1
 
 list[key()] or= 100
-ok list.join(' ') is '0 0 5 10'
+ok list.join(' ') is '0  5 10'
 
 count = 0
 
-list[key()] or= 100
+list[key()] ?= 100
 ok list.join(' ') is '0 100 5 10'
\ No newline at end of file