diff --git a/.eslintrc.yml b/.eslintrc.yml
index 69a728b..00c187e 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -19,7 +19,7 @@ rules:
 #  no-console: [ 2, { allow: [ warn, error ] } ]
   no-console: 0
   block-scoped-var: 2
-  complexity: [ 2, 15 ]
+  complexity: [ 2, 18 ]
   curly: [ 2, multi-or-nest, consistent ]
   dot-location: [ 2, property ]
   dot-notation: 2
diff --git a/keywords/uniqueItemProperties.js b/keywords/uniqueItemProperties.js
index 94df2fa..cd670da 100644
--- a/keywords/uniqueItemProperties.js
+++ b/keywords/uniqueItemProperties.js
@@ -16,7 +16,7 @@ module.exports = function defFunc(ajv) {
             if (scalar[k]) {
               var hash = {};
               for (i = data.length; i--;) {
-                if (typeof data[i] != 'object') continue;
+                if (!data[i] || typeof data[i] != 'object') continue;
                 var prop = data[i][key];
                 if (prop && typeof prop == 'object') continue;
                 if (typeof prop == 'string') prop = '"' + prop;
@@ -25,9 +25,9 @@ module.exports = function defFunc(ajv) {
               }
             } else {
               for (i = data.length; i--;) {
-                if (typeof data[i] != 'object') continue;
+                if (!data[i] || typeof data[i] != 'object') continue;
                 for (var j = i; j--;) {
-                  if (typeof data[j] == 'object' && equal(data[i][key], data[j][key]))
+                  if (data[j] && typeof data[j] == 'object' && equal(data[i][key], data[j][key]))
                     return false;
                 }
               }
diff --git a/spec/tests/uniqueItemProperties.json b/spec/tests/uniqueItemProperties.json
index 04caf6a..2d77f0e 100644
--- a/spec/tests/uniqueItemProperties.json
+++ b/spec/tests/uniqueItemProperties.json
@@ -395,5 +395,73 @@
         "valid": false
       }
     ]
+  },
+  {
+    "description": "uniqueItemProperties keyword with null item(s)",
+    "schema": {
+      "type": "array",
+      "uniqueItemProperties": ["id"],
+      "items": {
+        "properties": {
+          "id": {"type": "integer"}
+        }
+      }
+    },
+    "tests": [
+      {
+        "description": "with all unique ids and null items is valid",
+        "data": [
+          { "id": 1 },
+          { "id": 2 },
+          null,
+          null
+        ],
+        "valid": true
+      },
+      {
+        "description": "with non-unique ids and null item is invalid",
+        "data": [
+          { "id": 1 },
+          { "id": 1 },
+          null,
+          null
+        ],
+        "valid": false
+      }
+    ]
+  },
+  {
+    "description": "uniqueItemProperties keyword with null item(s) and object keys",
+    "schema": {
+      "type": "array",
+      "uniqueItemProperties": ["id"],
+      "items": {
+        "properties": {
+          "id": {"type": "object"}
+        }
+      }
+    },
+    "tests": [
+      {
+        "description": "with all unique ids and null items is valid",
+        "data": [
+          { "id": {"_id": 1} },
+          { "id": {"_id": 2} },
+          null,
+          null
+        ],
+        "valid": true
+      },
+      {
+        "description": "with non-unique ids and null item is invalid",
+        "data": [
+          { "id": {"_id": 1} },
+          { "id": {"_id": 1} },
+          null,
+          null
+        ],
+        "valid": false
+      }
+    ]
   }
 ]