diff --git a/objectivec/GPBMessage.h b/objectivec/GPBMessage.h
index 90d6991de2..2d9b67ebd3 100644
--- a/objectivec/GPBMessage.h
+++ b/objectivec/GPBMessage.h
@@ -510,10 +510,11 @@ CF_EXTERN_C_END
  * If the intent is to *replace* the message's unknown fields, call `-clearUnknownFields` first.
  *
  * Since the data from the GPBUnknownFields will always be well formed, this call will almost never
- * fail. What could cause it to fail is if the GPBUnknownFields contains a field values it is
- * and error for the message's schema - i.e.: if it contains a length delimited field where the
+ * fail. What could cause it to fail is if the GPBUnknownFields contains a field value that is
+ * an error for the message's schema - i.e.: if it contains a length delimited field where the
  * field number for the message is defined to be a _string_ field, however the length delimited
- * data provide is not a valid UTF8 string.
+ * data provide is not a valid UTF8 string, or if the field is a _packed_ number field, but the
+ * data provided is not a valid for that field.
  *
  * @param unknownFields     The unknown fields to merge the data from.
  * @param extensionRegistry The extension registry to use to look up extensions, can be `nil`.
diff --git a/objectivec/Tests/GPBUnknownFieldsTest.m b/objectivec/Tests/GPBUnknownFieldsTest.m
index c1e5e10634..42c3f7dc87 100644
--- a/objectivec/Tests/GPBUnknownFieldsTest.m
+++ b/objectivec/Tests/GPBUnknownFieldsTest.m
@@ -911,16 +911,32 @@
 }
 
 - (void)testMergeFailures {
-  // Valid data, pushes to the string just fine.
+  // Valid data, pushes to the fields just fine.
   {
     GPBUnknownFields* ufs = [[[GPBUnknownFields alloc] init] autorelease];
     [ufs addFieldNumber:TestAllTypes_FieldNumber_OptionalString
         lengthDelimited:DataFromCStr("abc")];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedInt32Array
+        lengthDelimited:DataFromBytes(0x01, 0x02)];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedFixed32Array
+        lengthDelimited:DataFromBytes(0x03, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00)];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedFixed64Array
+        lengthDelimited:DataFromBytes(0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00,
+                                      0x00, 0x00, 0x00, 0x00, 0x00, 0x00)];
     TestAllTypes* msg = [TestAllTypes message];
     NSError* error = nil;
     XCTAssertTrue([msg mergeUnknownFields:ufs extensionRegistry:nil error:&error]);
     XCTAssertNil(error);
     XCTAssertEqualObjects(msg.optionalString, @"abc");
+    XCTAssertEqual(msg.repeatedInt32Array.count, 2);
+    XCTAssertEqual([msg.repeatedInt32Array valueAtIndex:0], 1);
+    XCTAssertEqual([msg.repeatedInt32Array valueAtIndex:1], 2);
+    XCTAssertEqual(msg.repeatedFixed32Array.count, 2);
+    XCTAssertEqual([msg.repeatedFixed32Array valueAtIndex:0], 3);
+    XCTAssertEqual([msg.repeatedFixed32Array valueAtIndex:1], 4);
+    XCTAssertEqual(msg.repeatedFixed64Array.count, 2);
+    XCTAssertEqual([msg.repeatedFixed64Array valueAtIndex:0], 5);
+    XCTAssertEqual([msg.repeatedFixed64Array valueAtIndex:1], 6);
   }
 
   // Invalid UTF-8 causes a failure when pushed to the message.
@@ -933,6 +949,39 @@
     XCTAssertFalse([msg mergeUnknownFields:ufs extensionRegistry:nil error:&error]);
     XCTAssertNotNil(error);
   }
+
+  // Invalid packed varint causes a failure when pushed to the message.
+  {
+    GPBUnknownFields* ufs = [[[GPBUnknownFields alloc] init] autorelease];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedInt32Array
+        lengthDelimited:DataFromBytes(0xff)];  // Invalid varint
+    TestAllTypes* msg = [TestAllTypes message];
+    NSError* error = nil;
+    XCTAssertFalse([msg mergeUnknownFields:ufs extensionRegistry:nil error:&error]);
+    XCTAssertNotNil(error);
+  }
+
+  // Invalid packed fixed32 causes a failure when pushed to the message.
+  {
+    GPBUnknownFields* ufs = [[[GPBUnknownFields alloc] init] autorelease];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedFixed32Array
+        lengthDelimited:DataFromBytes(0x01, 0x00, 0x00)];  // Truncated fixed32
+    TestAllTypes* msg = [TestAllTypes message];
+    NSError* error = nil;
+    XCTAssertFalse([msg mergeUnknownFields:ufs extensionRegistry:nil error:&error]);
+    XCTAssertNotNil(error);
+  }
+
+  // Invalid packed fixed64 causes a failure when pushed to the message.
+  {
+    GPBUnknownFields* ufs = [[[GPBUnknownFields alloc] init] autorelease];
+    [ufs addFieldNumber:TestAllTypes_FieldNumber_RepeatedFixed64Array
+        lengthDelimited:DataFromBytes(0x01, 0x00, 0x00, 0x00, 0x00)];  // Truncated fixed64
+    TestAllTypes* msg = [TestAllTypes message];
+    NSError* error = nil;
+    XCTAssertFalse([msg mergeUnknownFields:ufs extensionRegistry:nil error:&error]);
+    XCTAssertNotNil(error);
+  }
 }
 
 - (void)testLargeVarint {