diff --git a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/Consistency.expected b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/Consistency.expected
index e69de29bb2d..f4ec03f6468 100644
--- a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/Consistency.expected
+++ b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/Consistency.expected
@@ -0,0 +1,2 @@
+| query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js:120 | did not expect an alert, but found an alert for PrototypePollutingAssignment | OK - 'object' is not Object.prototype itself (but possibly a copy) | PrototypePollutingAssignment |
+| query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js:124 | did not expect an alert, but found an alert for PrototypePollutingAssignment | OK - 'dest' is not Object.prototype itself (but possibly a copy) | PrototypePollutingAssignment |
diff --git a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/PrototypePollutingAssignment.expected b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/PrototypePollutingAssignment.expected
index 891aeff4221..0a5492e08c9 100644
--- a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/PrototypePollutingAssignment.expected
+++ b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/PrototypePollutingAssignment.expected
@@ -190,6 +190,26 @@ nodes
 | tst.js:105:5:105:17 | object[taint] |
 | tst.js:105:5:105:17 | object[taint] |
 | tst.js:105:12:105:16 | taint |
+| tst.js:116:9:116:38 | taint |
+| tst.js:116:17:116:38 | String( ... y.data) |
+| tst.js:116:24:116:37 | req.query.data |
+| tst.js:116:24:116:37 | req.query.data |
+| tst.js:119:9:119:51 | object |
+| tst.js:119:18:119:51 | Object. ... taint]) |
+| tst.js:119:32:119:33 | {} |
+| tst.js:119:32:119:33 | {} |
+| tst.js:119:36:119:50 | plainObj[taint] |
+| tst.js:119:45:119:49 | taint |
+| tst.js:120:5:120:10 | object |
+| tst.js:120:5:120:10 | object |
+| tst.js:122:9:122:17 | dest |
+| tst.js:122:16:122:17 | {} |
+| tst.js:123:19:123:22 | dest |
+| tst.js:123:19:123:22 | dest |
+| tst.js:123:25:123:39 | plainObj[taint] |
+| tst.js:123:34:123:38 | taint |
+| tst.js:124:5:124:8 | dest |
+| tst.js:124:5:124:8 | dest |
 edges
 | lib.js:1:38:1:40 | obj | lib.js:6:7:6:9 | obj |
 | lib.js:1:38:1:40 | obj | lib.js:6:7:6:9 | obj |
@@ -366,6 +386,26 @@ edges
 | tst.js:102:24:102:37 | req.query.data | tst.js:102:17:102:38 | String( ... y.data) |
 | tst.js:105:12:105:16 | taint | tst.js:105:5:105:17 | object[taint] |
 | tst.js:105:12:105:16 | taint | tst.js:105:5:105:17 | object[taint] |
+| tst.js:116:9:116:38 | taint | tst.js:119:45:119:49 | taint |
+| tst.js:116:9:116:38 | taint | tst.js:123:34:123:38 | taint |
+| tst.js:116:17:116:38 | String( ... y.data) | tst.js:116:9:116:38 | taint |
+| tst.js:116:24:116:37 | req.query.data | tst.js:116:17:116:38 | String( ... y.data) |
+| tst.js:116:24:116:37 | req.query.data | tst.js:116:17:116:38 | String( ... y.data) |
+| tst.js:119:9:119:51 | object | tst.js:120:5:120:10 | object |
+| tst.js:119:9:119:51 | object | tst.js:120:5:120:10 | object |
+| tst.js:119:18:119:51 | Object. ... taint]) | tst.js:119:9:119:51 | object |
+| tst.js:119:32:119:33 | {} | tst.js:119:18:119:51 | Object. ... taint]) |
+| tst.js:119:36:119:50 | plainObj[taint] | tst.js:119:18:119:51 | Object. ... taint]) |
+| tst.js:119:36:119:50 | plainObj[taint] | tst.js:119:32:119:33 | {} |
+| tst.js:119:36:119:50 | plainObj[taint] | tst.js:119:32:119:33 | {} |
+| tst.js:119:45:119:49 | taint | tst.js:119:36:119:50 | plainObj[taint] |
+| tst.js:122:9:122:17 | dest | tst.js:123:19:123:22 | dest |
+| tst.js:122:9:122:17 | dest | tst.js:123:19:123:22 | dest |
+| tst.js:122:9:122:17 | dest | tst.js:124:5:124:8 | dest |
+| tst.js:122:9:122:17 | dest | tst.js:124:5:124:8 | dest |
+| tst.js:122:16:122:17 | {} | tst.js:122:9:122:17 | dest |
+| tst.js:123:25:123:39 | plainObj[taint] | tst.js:122:16:122:17 | {} |
+| tst.js:123:34:123:38 | taint | tst.js:123:25:123:39 | plainObj[taint] |
 #select
 | lib.js:6:7:6:9 | obj | lib.js:1:43:1:46 | path | lib.js:6:7:6:9 | obj | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | lib.js:1:43:1:46 | path | library input |
 | lib.js:15:3:15:14 | obj[path[0]] | lib.js:14:38:14:41 | path | lib.js:15:3:15:14 | obj[path[0]] | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | lib.js:14:38:14:41 | path | library input |
@@ -394,3 +434,7 @@ edges
 | tst.js:94:5:94:37 | obj[req ... ', '')] | tst.js:94:9:94:19 | req.query.x | tst.js:94:5:94:37 | obj[req ... ', '')] | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:94:9:94:19 | req.query.x | user controlled input |
 | tst.js:97:5:97:46 | obj[req ... g, '')] | tst.js:97:9:97:19 | req.query.x | tst.js:97:5:97:46 | obj[req ... g, '')] | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:97:9:97:19 | req.query.x | user controlled input |
 | tst.js:105:5:105:17 | object[taint] | tst.js:102:24:102:37 | req.query.data | tst.js:105:5:105:17 | object[taint] | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:102:24:102:37 | req.query.data | user controlled input |
+| tst.js:119:32:119:33 | {} | tst.js:116:24:116:37 | req.query.data | tst.js:119:32:119:33 | {} | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:116:24:116:37 | req.query.data | user controlled input |
+| tst.js:120:5:120:10 | object | tst.js:116:24:116:37 | req.query.data | tst.js:120:5:120:10 | object | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:116:24:116:37 | req.query.data | user controlled input |
+| tst.js:123:19:123:22 | dest | tst.js:116:24:116:37 | req.query.data | tst.js:123:19:123:22 | dest | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:116:24:116:37 | req.query.data | user controlled input |
+| tst.js:124:5:124:8 | dest | tst.js:116:24:116:37 | req.query.data | tst.js:124:5:124:8 | dest | This assignment may alter Object.prototype if a malicious '__proto__' string is injected from $@. | tst.js:116:24:116:37 | req.query.data | user controlled input |
diff --git a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js
index 517d7d10230..d301fe40bf6 100644
--- a/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js
+++ b/javascript/ql/test/query-tests/Security/CWE-915/PrototypePollutingAssignment/tst.js
@@ -103,11 +103,23 @@ app.get('/bar', (req, res) => {
 
     let object = {};
     object[taint][taint] = taint; // NOT OK
-    
+
     const bad = ["__proto__", "constructor"];
     if (bad.includes(taint)) {
         return;
     }
 
     object[taint][taint] = taint; // OK
-});
\ No newline at end of file
+});
+
+app.get('/assign', (req, res) => {
+    let taint = String(req.query.data);
+    let plainObj = {};
+
+    let object = Object.assign({}, plainObj[taint]);
+    object[taint] = taint; // OK - 'object' is not Object.prototype itself (but possibly a copy)
+
+    let dest = {};
+    Object.assign(dest, plainObj[taint]);
+    dest[taint] = taint; // OK - 'dest' is not Object.prototype itself (but possibly a copy)
+});