diff --git a/stepmania/src/RageFileDriverDeflate.cpp b/stepmania/src/RageFileDriverDeflate.cpp
index 23bcddf7d2..5ad0130a51 100644
--- a/stepmania/src/RageFileDriverDeflate.cpp
+++ b/stepmania/src/RageFileDriverDeflate.cpp
@@ -312,7 +312,7 @@ int RageFileObjDeflate::FlushInternal()
  * Parse a .gz file, check the header CRC16 if present, and return the data
  * CRC32 and a decompressor.
  */
-RageFileBasic *GunzipFile( RageFileBasic &file, RString &sError, uint32_t *iCRC32 )
+RageFileObjInflate *GunzipFile( RageFileBasic &file, RString &sError, uint32_t *iCRC32 )
 {
 	sError = "";
 
diff --git a/stepmania/src/RageFileDriverDeflate.h b/stepmania/src/RageFileDriverDeflate.h
index 361fbd7403..b0929e8e32 100644
--- a/stepmania/src/RageFileDriverDeflate.h
+++ b/stepmania/src/RageFileDriverDeflate.h
@@ -66,7 +66,7 @@ private:
 	int m_iDataStartOffset;
 };
 
-RageFileBasic *GunzipFile( RageFileBasic &file, RString &sError, uint32_t *iCRC32 );
+RageFileObjInflate *GunzipFile( RageFileBasic &file, RString &sError, uint32_t *iCRC32 );
 
 /* Quick helpers: */
 void GzipString( const RString &sIn, RString &sOut );