diff --git a/payload_generator/ab_generator.cc b/payload_generator/ab_generator.cc
index 459b3b9..065408b 100644
--- a/payload_generator/ab_generator.cc
+++ b/payload_generator/ab_generator.cc
@@ -38,6 +38,7 @@
     const PartitionConfig& new_part,
     BlobFileWriter* blob_file,
     vector<AnnotatedOperation>* aops) {
+  TEST_AND_RETURN_FALSE(old_part.name == new_part.name);
 
   ssize_t hard_chunk_blocks = (config.hard_chunk_size == -1 ? -1 :
                                config.hard_chunk_size / config.block_size);
@@ -52,7 +53,7 @@
       soft_chunk_blocks,
       blob_file,
       true));  // src_ops_allowed
-  LOG(INFO) << "done reading " << PartitionNameString(new_part.name);
+  LOG(INFO) << "done reading " << new_part.name;
 
   TEST_AND_RETURN_FALSE(FragmentOperations(aops,
                                            new_part.path,
diff --git a/payload_generator/delta_diff_utils_unittest.cc b/payload_generator/delta_diff_utils_unittest.cc
index 4d81632..6b23197 100644
--- a/payload_generator/delta_diff_utils_unittest.cc
+++ b/payload_generator/delta_diff_utils_unittest.cc
@@ -143,8 +143,8 @@
 
   // Old and new temporary partitions used in the tests. These are initialized
   // with
-  PartitionConfig old_part_{PartitionName::kRootfs};
-  PartitionConfig new_part_{PartitionName::kRootfs};
+  PartitionConfig old_part_{"part"};
+  PartitionConfig new_part_{"part"};
 
   // The file holding the output blob from the various diff utils functions.
   string blob_path_;
diff --git a/payload_generator/full_update_generator.cc b/payload_generator/full_update_generator.cc
index 101f28a..7ece2ad 100644
--- a/payload_generator/full_update_generator.cc
+++ b/payload_generator/full_update_generator.cc
@@ -146,7 +146,7 @@
 
   size_t chunk_blocks = full_chunk_size / config.block_size;
   size_t max_threads = std::max(sysconf(_SC_NPROCESSORS_ONLN), 4L);
-  LOG(INFO) << "Compressing partition " << PartitionNameString(new_part.name)
+  LOG(INFO) << "Compressing partition " << new_part.name
             << " from " << new_part.path << " splitting in chunks of "
             << chunk_blocks << " blocks (" << config.block_size
             << " bytes each) using " << max_threads << " threads";
@@ -164,8 +164,6 @@
   chunk_processors.reserve(num_chunks);
   blob_file->SetTotalBlobs(num_chunks);
 
-  const string part_name_str = PartitionNameString(new_part.name);
-
   for (size_t i = 0; i < num_chunks; ++i) {
     size_t start_block = i * chunk_blocks;
     // The last chunk could be smaller.
@@ -176,7 +174,7 @@
     // ChunkProcessor will set the rest.
     AnnotatedOperation* aop = aops->data() + i;
     aop->name = base::StringPrintf("<%s-operation-%" PRIuS ">",
-                                   part_name_str.c_str(), i);
+                                   new_part.name.c_str(), i);
     Extent* dst_extent = aop->op.add_dst_extents();
     dst_extent->set_start_block(start_block);
     dst_extent->set_num_blocks(num_blocks);
diff --git a/payload_generator/full_update_generator_unittest.cc b/payload_generator/full_update_generator_unittest.cc
index ac37158..2f39126 100644
--- a/payload_generator/full_update_generator_unittest.cc
+++ b/payload_generator/full_update_generator_unittest.cc
@@ -52,7 +52,7 @@
   }
 
   PayloadGenerationConfig config_;
-  PartitionConfig new_part_conf{PartitionName::kRootfs};
+  PartitionConfig new_part_conf{"part"};
 
   vector<AnnotatedOperation> aops;
 
diff --git a/payload_generator/inplace_generator.cc b/payload_generator/inplace_generator.cc
index 9d108bd..0cfbe02 100644
--- a/payload_generator/inplace_generator.cc
+++ b/payload_generator/inplace_generator.cc
@@ -790,15 +790,16 @@
     const PartitionConfig& new_part,
     BlobFileWriter* blob_file,
     vector<AnnotatedOperation>* aops) {
+  TEST_AND_RETURN_FALSE(old_part.name == new_part.name);
+
   ssize_t hard_chunk_blocks = (config.hard_chunk_size == -1 ? -1 :
                                config.hard_chunk_size / config.block_size);
   size_t soft_chunk_blocks = config.soft_chunk_size / config.block_size;
   uint64_t partition_size = new_part.size;
-  if (new_part.name == PartitionName::kRootfs)
+  if (new_part.name == kLegacyPartitionNameRoot)
     partition_size = config.rootfs_partition_size;
 
-  const string part_name = PartitionNameString(new_part.name);
-  LOG(INFO) << "Delta compressing " << part_name << " partition...";
+  LOG(INFO) << "Delta compressing " << new_part.name << " partition...";
   TEST_AND_RETURN_FALSE(
     diff_utils::DeltaReadPartition(aops,
                                    old_part,
@@ -807,7 +808,7 @@
                                    soft_chunk_blocks,
                                    blob_file,
                                    false));  // src_ops_allowed
-  LOG(INFO) << "Done reading " << part_name;
+  LOG(INFO) << "Done reading " << new_part.name;
 
   TEST_AND_RETURN_FALSE(
     ResolveReadAfterWriteDependencies(new_part,
@@ -815,7 +816,7 @@
                                       config.block_size,
                                       blob_file,
                                       aops));
-  LOG(INFO) << "Done reordering " << part_name;
+  LOG(INFO) << "Done reordering " << new_part.name;
   return true;
 }
 
diff --git a/payload_generator/inplace_generator_unittest.cc b/payload_generator/inplace_generator_unittest.cc
index 1cc20cf..d6430c8 100644
--- a/payload_generator/inplace_generator_unittest.cc
+++ b/payload_generator/inplace_generator_unittest.cc
@@ -608,7 +608,7 @@
     aops.push_back(aop);
   }
 
-  PartitionConfig part(PartitionName::kRootfs);
+  PartitionConfig part("part");
   part.path = "/dev/zero";
   part.size = num_blocks * block_size;
 
diff --git a/payload_generator/payload_generation_config.cc b/payload_generator/payload_generation_config.cc
index ecf9627..a2d9311 100644
--- a/payload_generator/payload_generation_config.cc
+++ b/payload_generator/payload_generation_config.cc
@@ -26,16 +26,6 @@
 
 namespace chromeos_update_engine {
 
-std::string PartitionNameString(PartitionName name) {
-  switch (name) {
-    case PartitionName::kKernel:
-      return "kernel";
-    case PartitionName::kRootfs:
-      return "rootfs";
-  }
-  return "other";
-}
-
 bool PartitionConfig::ValidateExists() const {
   TEST_AND_RETURN_FALSE(!path.empty());
   TEST_AND_RETURN_FALSE(utils::FileExists(path.c_str()));
@@ -50,7 +40,7 @@
   if (path.empty())
     return true;
   fs_interface.reset();
-  if (name == PartitionName::kRootfs) {
+  if (utils::IsExtFilesystem(path)) {
     fs_interface = Ext2Filesystem::CreateFromFile(path);
   }
 
@@ -58,7 +48,7 @@
     // Fall back to a RAW filesystem.
     TEST_AND_RETURN_FALSE(size % kBlockSize == 0);
     fs_interface = RawFilesystem::Create(
-      "<" + PartitionNameString(name) + "-partition>",
+      "<" + name + "-partition>",
       kBlockSize,
       size / kBlockSize);
   }
diff --git a/payload_generator/payload_generation_config.h b/payload_generator/payload_generation_config.h
index 4e99688..b7bd484 100644
--- a/payload_generator/payload_generation_config.h
+++ b/payload_generator/payload_generation_config.h
@@ -23,22 +23,14 @@
 #include <string>
 #include <vector>
 
+#include "update_engine/payload_constants.h"
 #include "update_engine/payload_generator/filesystem_interface.h"
 #include "update_engine/update_metadata.pb.h"
 
 namespace chromeos_update_engine {
 
-// The list different kind of partitions supported by the updater.
-enum class PartitionName {
-  kKernel,
-  kRootfs,
-};
-
-// Return a string name for the PartitionName.
-std::string PartitionNameString(PartitionName name);
-
 struct PartitionConfig {
-  explicit PartitionConfig(PartitionName name) : name(name) {}
+  explicit PartitionConfig(std::string name) : name(name) {}
 
   // Returns whether the PartitionConfig is not an empty image and all the
   // fields are set correctly to a valid image file.
@@ -64,7 +56,7 @@
   // files.
   std::unique_ptr<FilesystemInterface> fs_interface;
 
-  PartitionName name;
+  std::string name;
 };
 
 // The ImageConfig struct describes a pair of binaries kernel and rootfs and the
@@ -88,8 +80,8 @@
   ImageInfo image_info;
 
   // The updated partitions.
-  PartitionConfig rootfs = PartitionConfig{PartitionName::kRootfs};
-  PartitionConfig kernel = PartitionConfig{PartitionName::kKernel};
+  PartitionConfig rootfs = PartitionConfig{kLegacyPartitionNameRoot};
+  PartitionConfig kernel = PartitionConfig{kLegacyPartitionNameKernel};
 };
 
 // The PayloadGenerationConfig struct encapsulates all the configuration to