diff --git a/lib/internal/util/comparisons.js b/lib/internal/util/comparisons.js
index 9adffea09a14c5..43a8921f657130 100644
--- a/lib/internal/util/comparisons.js
+++ b/lib/internal/util/comparisons.js
@@ -416,9 +416,7 @@ function mapMightHaveLoosePrim(a, b, prim, item, memo) {
       !innerDeepEqual(item, curB, false, memo)) {
     return false;
   }
-  const curA = a.get(altValue);
-  return curA === undefined && a.has(altValue) ||
-         innerDeepEqual(item, curA, false, memo);
+  return !a.has(altValue) && innerDeepEqual(item, curB, false, memo);
 }
 
 function setEquiv(a, b, strict, memo) {
diff --git a/test/parallel/test-assert-deep.js b/test/parallel/test-assert-deep.js
index a4533977608c00..db93f3b6e717bb 100644
--- a/test/parallel/test-assert-deep.js
+++ b/test/parallel/test-assert-deep.js
@@ -394,6 +394,14 @@ assertOnlyDeepEqual(
   new Map([[1, {}]]),
   new Map([[true, {}]])
 );
+assertOnlyDeepEqual(
+  new Map([[undefined, true]]),
+  new Map([[null, true]])
+);
+assertNotDeepOrStrict(
+  new Map([[undefined, true]]),
+  new Map([[true, true]])
+);
 
 // GH-6416. Make sure circular refs don't throw.
 {