diff --git a/include/androidfw/AssetManager.h b/include/androidfw/AssetManager.h
index ac47900..a13dd16 100644
--- a/include/androidfw/AssetManager.h
+++ b/include/androidfw/AssetManager.h
@@ -231,7 +231,7 @@
      * corresponding overlay package.
      */
     bool createIdmap(const char* targetApkPath, const char* overlayApkPath,
-        uint32_t targetCrc, uint32_t overlayCrc, uint32_t** outData, uint32_t* outSize);
+        uint32_t targetCrc, uint32_t overlayCrc, uint32_t** outData, size_t* outSize);
 
 private:
     struct asset_path
diff --git a/include/androidfw/ResourceTypes.h b/include/androidfw/ResourceTypes.h
index c022818..05411ea 100644
--- a/include/androidfw/ResourceTypes.h
+++ b/include/androidfw/ResourceTypes.h
@@ -1284,7 +1284,7 @@
     ~ResTable();
 
     status_t add(Asset* asset, const int32_t cookie, bool copyData,
-                 const void* idmap);
+                 const void* idmap = NULL);
     status_t add(const void *data, size_t size);
     status_t add(ResTable* src);
 
@@ -1548,7 +1548,7 @@
     status_t createIdmap(const ResTable& overlay,
             uint32_t targetCrc, uint32_t overlayCrc,
             const char* targetPath, const char* overlayPath,
-            void** outData, uint32_t* outSize) const;
+            void** outData, size_t* outSize) const;
 
     enum {
         IDMAP_HEADER_SIZE_BYTES = 3 * sizeof(uint32_t) + 2 * 256,
diff --git a/libs/androidfw/AssetManager.cpp b/libs/androidfw/AssetManager.cpp
index 05a948d..5069958 100644
--- a/libs/androidfw/AssetManager.cpp
+++ b/libs/androidfw/AssetManager.cpp
@@ -285,7 +285,7 @@
  }
 
 bool AssetManager::createIdmap(const char* targetApkPath, const char* overlayApkPath,
-        uint32_t targetCrc, uint32_t overlayCrc, uint32_t** outData, uint32_t* outSize)
+        uint32_t targetCrc, uint32_t overlayCrc, uint32_t** outData, size_t* outSize)
 {
     AutoMutex _l(mLock);
     const String8 paths[2] = { String8(targetApkPath), String8(overlayApkPath) };