diff --git a/delta_performer.cc b/delta_performer.cc
index c20614d..69ffbc1 100644
--- a/delta_performer.cc
+++ b/delta_performer.cc
@@ -39,6 +39,8 @@
 
 const uint64_t DeltaPerformer::kDeltaVersionSize = 8;
 const uint64_t DeltaPerformer::kDeltaManifestSizeSize = 8;
+const uint64_t DeltaPerformer::kSupportedMajorPayloadVersion = 1;
+
 const char DeltaPerformer::kUpdatePayloadPublicKeyPath[] =
     "/usr/share/update_engine/update-payload-key.pub.pem";
 const unsigned DeltaPerformer::kProgressLogMaxChunks = 10;
@@ -247,6 +249,11 @@
 
 }  // namespace {}
 
+uint64_t DeltaPerformer::GetVersionOffset() {
+ // Manifest size is stored right after the magic string and the version.
+ return strlen(kDeltaMagic);
+}
+
 uint64_t DeltaPerformer::GetManifestSizeOffset() {
  // Manifest size is stored right after the magic string and the version.
  return strlen(kDeltaMagic) + kDeltaVersionSize;
@@ -279,8 +286,22 @@
     return kMetadataParseError;
   }
 
-  // TODO(jaysri): Compare the version number and skip unknown manifest
-  // versions. We don't check the version at all today.
+  // Extract the payload version from the metadata.
+  uint64_t major_payload_version;
+  COMPILE_ASSERT(sizeof(major_payload_version) == kDeltaVersionSize,
+                 major_payload_version_size_mismatch);
+  memcpy(&major_payload_version,
+         &payload[GetVersionOffset()],
+         kDeltaVersionSize);
+  // switch big endian to host
+  major_payload_version = be64toh(major_payload_version);
+
+  if (major_payload_version != kSupportedMajorPayloadVersion) {
+    LOG(ERROR) << "Bad payload format -- unsupported payload version: "
+               << major_payload_version;
+    *error = kErrorCodeUnsupportedMajorPayloadVersion;
+    return kMetadataParseError;
+  }
 
   // Next, parse the manifest size.
   uint64_t manifest_size;
diff --git a/delta_performer.h b/delta_performer.h
index 7943d7a..a9cbe44 100644
--- a/delta_performer.h
+++ b/delta_performer.h
@@ -36,6 +36,7 @@
 
   static const uint64_t kDeltaVersionSize;
   static const uint64_t kDeltaManifestSizeSize;
+  static const uint64_t kSupportedMajorPayloadVersion;
   static const char kUpdatePayloadPublicKeyPath[];
 
   // Defines the granularity of progress logging in terms of how many "completed
@@ -163,15 +164,18 @@
     public_key_path_ = public_key_path;
   }
 
-  // Returns the byte offset at which the manifest protobuf begins in a
-  // payload.
-  static uint64_t GetManifestOffset();
+  // Returns the byte offset at which the payload version can be found.
+  static uint64_t GetVersionOffset();
 
   // Returns the byte offset where the size of the manifest is stored in
   // a payload. This offset precedes the actual start of the manifest
   // that's returned by the GetManifestOffset method.
   static uint64_t GetManifestSizeOffset();
 
+  // Returns the byte offset at which the manifest protobuf begins in a
+  // payload.
+  static uint64_t GetManifestOffset();
+
  private:
   friend class DeltaPerformerTest;
   FRIEND_TEST(DeltaPerformerTest, IsIdempotentOperationTest);
diff --git a/error_code.h b/error_code.h
index 65a5533..5853c1b 100644
--- a/error_code.h
+++ b/error_code.h
@@ -53,11 +53,15 @@
   kErrorCodePostinstallPowerwashError = 41,
   kErrorCodeUpdateCanceledByChannelChange = 42,
   kErrorCodePostinstallFirmwareRONotUpdatable = 43,
+  kErrorCodeUnsupportedMajorPayloadVersion = 44,
+  kErrorCodeUnsupportedMinorPayloadVersion = 45,
 
-  // Note: When adding new error codes, please remember to add the
-  // error into one of the buckets in PayloadState::UpdateFailed method so
-  // that the retries across URLs and the payload backoff mechanism work
-  // correctly for those new error codes.
+  // VERY IMPORTANT! When adding new error codes:
+  //
+  // 1) Update tools/metrics/histograms/histograms.xml in Chrome.
+  //
+  // 2) Update the assorted switch statements in update_engine which won't
+  //    build until this case is added.
 
   // Any code above this is sent to both Omaha and UMA as-is, except
   // kErrorCodeOmahaErrorInHTTPResponse (see error code 2000 for more details).
diff --git a/payload_state.cc b/payload_state.cc
index 162848a..9839a2b 100644
--- a/payload_state.cc
+++ b/payload_state.cc
@@ -220,6 +220,8 @@
     case kErrorCodeDownloadOperationHashMissingError:
     case kErrorCodeDownloadMetadataSignatureMissingError:
     case kErrorCodePayloadMismatchedType:
+    case kErrorCodeUnsupportedMajorPayloadVersion:
+    case kErrorCodeUnsupportedMinorPayloadVersion:
       IncrementUrlIndex();
       break;
 
diff --git a/payload_state_unittest.cc b/payload_state_unittest.cc
index ab59331..ec79950 100644
--- a/payload_state_unittest.cc
+++ b/payload_state_unittest.cc
@@ -90,7 +90,7 @@
 class PayloadStateTest : public ::testing::Test { };
 
 TEST(PayloadStateTest, DidYouAddANewErrorCode) {
-  if (kErrorCodeUmaReportedMax != 44) {
+  if (kErrorCodeUmaReportedMax != 46) {
     LOG(ERROR) << "The following failure is intentional. If you added a new "
                << "ErrorCode enum value, make sure to add it to the "
                << "PayloadState::UpdateFailed method and then update this test "
diff --git a/utils.cc b/utils.cc
index 5d32466..f23f31f 100644
--- a/utils.cc
+++ b/utils.cc
@@ -1000,6 +1000,10 @@
       return "kErrorCodeSpecialFlags";
     case kErrorCodePostinstallFirmwareRONotUpdatable:
       return "kErrorCodePostinstallFirmwareRONotUpdatable";
+    case kErrorCodeUnsupportedMajorPayloadVersion:
+      return "kErrorCodeUnsupportedMajorPayloadVersion";
+    case kErrorCodeUnsupportedMinorPayloadVersion:
+      return "kErrorCodeUnsupportedMinorPayloadVersion";
     // Don't add a default case to let the compiler warn about newly added
     // error codes which should be added here.
   }