diff --git a/packages/collection-diff/index.cjs b/packages/collection-diff/index.cjs
index 5f4fa3400..0c2daf6a9 100644
--- a/packages/collection-diff/index.cjs
+++ b/packages/collection-diff/index.cjs
@@ -173,7 +173,7 @@ function diff(obj1, obj2, pathConverter) {
     var obj1AtKey = obj1[key];
     var obj2AtKey = obj2[key];
 
-    if(!(key in obj1) && obj2AtKey) {
+    if(!(key in obj1) && (key in obj2)) {
       var obj2Value = obj2AtKey;
       permutation.add.push({
         op: 'add',
diff --git a/packages/collection-diff/index.mjs b/packages/collection-diff/index.mjs
index 7c32c57f5..f965f7646 100644
--- a/packages/collection-diff/index.mjs
+++ b/packages/collection-diff/index.mjs
@@ -167,7 +167,7 @@ function diff(obj1, obj2, pathConverter) {
     var obj1AtKey = obj1[key];
     var obj2AtKey = obj2[key];
 
-    if(!(key in obj1) && obj2AtKey) {
+    if(!(key in obj1) && (key in obj2)) {
       var obj2Value = obj2AtKey;
       permutation.add.push({
         op: 'add',
diff --git a/test/collection-diff/index.cjs b/test/collection-diff/index.cjs
index 5c230686a..166879663 100644
--- a/test/collection-diff/index.cjs
+++ b/test/collection-diff/index.cjs
@@ -10,7 +10,7 @@ var {
 var compare = require('../../packages/collection-compare');
 
 test('flat objects', function(t) {
-  t.plan(8);
+  t.plan(10);
 
   var obj1 = {a: 4, b: 5};
   var obj2 = {a: 3, b: 5};
@@ -58,6 +58,20 @@ test('flat objects', function(t) {
       {op: 'replace', path: ['b'], value: 5},
     ])
   );
+  t.ok(
+    compare(diff(obj3, obj4), [
+      { op: 'remove', path: [ 'c' ] },
+      { op: 'replace', path: [ 'a' ], value: 3 },
+      { op: 'add', path: [ 'b' ], value: null }
+    ])
+  );
+  t.ok(
+    compare(diff(obj4, obj3), [
+      { op: 'remove', path: [ 'b' ] },
+      { op: 'replace', path: [ 'a' ], value: 4 },
+      { op: 'add', path: [ 'c' ], value: 5 }
+    ])
+  );
 });
 
 test('flat null and undefined', function(t) {