diff --git a/src/utils.js b/src/utils.js
index 92a9f475d88a..61c51367c59a 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -309,6 +309,13 @@ function isOnlyOneTruthy(a, b) {
   return !!(!!a ^ !!b);
 }
 
+/**
+ * Returns true if both parameters are undefined
+ */
+function isBothUndefined(a, b) {
+  return isUndefined(a) && isUndefined(b);
+}
+
 /**
  * Returns true if the two input exception interfaces have the same content
  */
@@ -320,6 +327,9 @@ function isSameException(ex1, ex2) {
 
   if (ex1.type !== ex2.type || ex1.value !== ex2.value) return false;
 
+  // in case both stacktraces are undefined, we can't decide so default to false
+  if (isBothUndefined(ex1.stacktrace, ex2.stacktrace)) return false;
+
   return isSameStacktrace(ex1.stacktrace, ex2.stacktrace);
 }
 
diff --git a/test/raven.test.js b/test/raven.test.js
index 486881310d80..9814522c29d0 100644
--- a/test/raven.test.js
+++ b/test/raven.test.js
@@ -3431,6 +3431,14 @@ describe('Raven (private methods)', function() {
         data.exception.values[0].stacktrace.frames = [];
         assert.isFalse(Raven._isRepeatData(data));
       });
+
+      it('should not blown if both stacktraces are undefined', function() {
+        Raven._lastData.exception.values[0].stacktrace = undefined;
+        var data1 = JSON.parse(JSON.stringify(Raven._lastData)); // copy
+        var data2 = JSON.parse(JSON.stringify(Raven._lastData)); // copy
+        assert.isFalse(Raven._isRepeatData(data1));
+        assert.isFalse(Raven._isRepeatData(data2));
+      });
     });
   });
 });