diff --git a/libs/androidfw/LoadedArsc.cpp b/libs/androidfw/LoadedArsc.cpp
index 621d8c0..bd7b804 100644
--- a/libs/androidfw/LoadedArsc.cpp
+++ b/libs/androidfw/LoadedArsc.cpp
@@ -416,7 +416,9 @@
   ATRACE_CALL();
   std::unique_ptr<LoadedPackage> loaded_package{new LoadedPackage()};
 
-  const ResTable_package* header = chunk.header<ResTable_package>();
+  constexpr size_t kMinPackageSize =
+      sizeof(ResTable_package) - sizeof(ResTable_package::typeIdOffset);
+  const ResTable_package* header = chunk.header<ResTable_package, kMinPackageSize>();
   if (header == nullptr) {
     LOG(ERROR) << "Chunk RES_TABLE_PACKAGE_TYPE is too small.";
     return {};
diff --git a/tools/aapt2/Main.cpp b/tools/aapt2/Main.cpp
index 5e9b81a..36c1de6 100644
--- a/tools/aapt2/Main.cpp
+++ b/tools/aapt2/Main.cpp
@@ -25,7 +25,7 @@
 static const char* sMajorVersion = "2";
 
 // Update minor version whenever a feature or flag is added.
-static const char* sMinorVersion = "11";
+static const char* sMinorVersion = "12";
 
 int PrintVersion() {
   std::cerr << "Android Asset Packaging Tool (aapt) " << sMajorVersion << "."
diff --git a/tools/aapt2/readme.md b/tools/aapt2/readme.md
index 9899f80..2e674bd 100644
--- a/tools/aapt2/readme.md
+++ b/tools/aapt2/readme.md
@@ -1,5 +1,13 @@
 # Android Asset Packaging Tool 2.0 (AAPT2) release notes
 
+## Version 2.12
+### `aapt2 optimize ...`
+- aapt2 optimize now understands map (complex) values under the type `id`. It ignores their
+  contents and interprets them as a sentinel `id` type. This was added to support existing
+  apps that build with their `id` types as map values.
+  AAPT and AAPT2 always generate a simple value for the type `ID`, so it is unclear how some
+  these apps are encoded.
+
 ## Version 2.11
 ### `aapt2 link ...`
 - Adds the ability to specify assets directories with the -A parameter. Assets work just like
diff --git a/tools/aapt2/unflatten/BinaryResourceParser.cpp b/tools/aapt2/unflatten/BinaryResourceParser.cpp
index 66bcfa0..35bf618 100644
--- a/tools/aapt2/unflatten/BinaryResourceParser.cpp
+++ b/tools/aapt2/unflatten/BinaryResourceParser.cpp
@@ -168,10 +168,11 @@
 }
 
 bool BinaryResourceParser::ParsePackage(const ResChunk_header* chunk) {
-  const ResTable_package* package_header = ConvertTo<ResTable_package>(chunk);
+  constexpr size_t kMinPackageSize =
+      sizeof(ResTable_package) - sizeof(ResTable_package::typeIdOffset);
+  const ResTable_package* package_header = ConvertTo<ResTable_package, kMinPackageSize>(chunk);
   if (!package_header) {
-    context_->GetDiagnostics()->Error(DiagMessage(source_)
-                                      << "corrupt ResTable_package chunk");
+    context_->GetDiagnostics()->Error(DiagMessage(source_) << "corrupt ResTable_package chunk");
     return false;
   }
 
@@ -498,8 +499,14 @@
       return ParseArray(name, config, map);
     case ResourceType::kPlurals:
       return ParsePlural(name, config, map);
+    case ResourceType::kId:
+      // Special case: An ID is not a bag, but some apps have defined the auto-generated
+      // IDs that come from declaring an enum value in an attribute as an empty map...
+      // We can ignore the value here.
+      return util::make_unique<Id>();
     default:
-      LOG(FATAL) << "unknown map type";
+      context_->GetDiagnostics()->Error(DiagMessage() << "illegal map type '" << ToString(name.type)
+                                                      << "' (" << (int)name.type << ")");
       break;
   }
   return {};