diff --git a/reactos/dll/win32/avifil32/acmstream.c b/reactos/dll/win32/avifil32/acmstream.c
index 6cda8c9f567..1501f41e298 100644
--- a/reactos/dll/win32/avifil32/acmstream.c
+++ b/reactos/dll/win32/avifil32/acmstream.c
@@ -23,7 +23,6 @@
 #include "winbase.h"
 #include "wingdi.h"
 #include "winuser.h"
-#include "winnls.h"
 #include "winerror.h"
 #include "mmsystem.h"
 #include "vfw.h"
diff --git a/reactos/dll/win32/avifil32/api.c b/reactos/dll/win32/avifil32/api.c
index 92c67748c96..592bac34b7b 100644
--- a/reactos/dll/win32/avifil32/api.c
+++ b/reactos/dll/win32/avifil32/api.c
@@ -17,7 +17,6 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
-#include <assert.h>
 #include <stdarg.h>
 
 #define COBJMACROS
diff --git a/reactos/dll/win32/avifil32/avifile.c b/reactos/dll/win32/avifil32/avifile.c
index f989c795254..3ed63868432 100644
--- a/reactos/dll/win32/avifil32/avifile.c
+++ b/reactos/dll/win32/avifil32/avifile.c
@@ -210,19 +210,19 @@ static HRESULT AVIFILE_AddFrame(IAVIStreamImpl *This, DWORD ckid, DWORD size,
 static HRESULT AVIFILE_AddRecord(IAVIFileImpl *This);
 static DWORD   AVIFILE_ComputeMoviStart(IAVIFileImpl *This);
 static void    AVIFILE_ConstructAVIStream(IAVIFileImpl *paf, DWORD nr,
-					  LPAVISTREAMINFOW asi);
+					  const AVISTREAMINFOW *asi);
 static void    AVIFILE_DestructAVIStream(IAVIStreamImpl *This);
 static HRESULT AVIFILE_LoadFile(IAVIFileImpl *This);
-static HRESULT AVIFILE_LoadIndex(IAVIFileImpl *This, DWORD size, DWORD offset);
-static HRESULT AVIFILE_ParseIndex(IAVIFileImpl *This, AVIINDEXENTRY *lp,
+static HRESULT AVIFILE_LoadIndex(const IAVIFileImpl *This, DWORD size, DWORD offset);
+static HRESULT AVIFILE_ParseIndex(const IAVIFileImpl *This, AVIINDEXENTRY *lp,
 				  LONG count, DWORD pos, BOOL *bAbsolute);
 static HRESULT AVIFILE_ReadBlock(IAVIStreamImpl *This, DWORD start,
 				 LPVOID buffer, LONG size);
-static void    AVIFILE_SamplesToBlock(IAVIStreamImpl *This, LPLONG pos,
+static void    AVIFILE_SamplesToBlock(const IAVIStreamImpl *This, LPLONG pos,
 				      LPLONG offset);
 static HRESULT AVIFILE_SaveFile(IAVIFileImpl *This);
-static HRESULT AVIFILE_SaveIndex(IAVIFileImpl *This);
-static ULONG   AVIFILE_SearchStream(IAVIFileImpl *This, DWORD fccType,
+static HRESULT AVIFILE_SaveIndex(const IAVIFileImpl *This);
+static ULONG   AVIFILE_SearchStream(const IAVIFileImpl *This, DWORD fccType,
 				    LONG lSkip);
 static void    AVIFILE_UpdateInfo(IAVIFileImpl *This);
 static HRESULT AVIFILE_WriteBlock(IAVIStreamImpl *This, DWORD block,
@@ -1502,7 +1502,7 @@ static DWORD   AVIFILE_ComputeMoviStart(IAVIFileImpl *This)
   return dwPos;
 }
 
-static void    AVIFILE_ConstructAVIStream(IAVIFileImpl *paf, DWORD nr, LPAVISTREAMINFOW asi)
+static void AVIFILE_ConstructAVIStream(IAVIFileImpl *paf, DWORD nr, const AVISTREAMINFOW *asi)
 {
   IAVIStreamImpl *pstream;
 
@@ -1902,7 +1902,7 @@ static HRESULT AVIFILE_LoadFile(IAVIFileImpl *This)
   return AVIERR_OK;
 }
 
-static HRESULT AVIFILE_LoadIndex(IAVIFileImpl *This, DWORD size, DWORD offset)
+static HRESULT AVIFILE_LoadIndex(const IAVIFileImpl *This, DWORD size, DWORD offset)
 {
   AVIINDEXENTRY *lp;
   DWORD          pos, n;
@@ -1975,7 +1975,7 @@ static HRESULT AVIFILE_LoadIndex(IAVIFileImpl *This, DWORD size, DWORD offset)
   return hr;
 }
 
-static HRESULT AVIFILE_ParseIndex(IAVIFileImpl *This, AVIINDEXENTRY *lp,
+static HRESULT AVIFILE_ParseIndex(const IAVIFileImpl *This, AVIINDEXENTRY *lp,
 				  LONG count, DWORD pos, BOOL *bAbsolute)
 {
   if (lp == NULL)
@@ -2064,8 +2064,7 @@ static HRESULT AVIFILE_ReadBlock(IAVIStreamImpl *This, DWORD pos,
   return AVIERR_OK;
 }
 
-static void    AVIFILE_SamplesToBlock(IAVIStreamImpl *This, LPLONG pos,
-				      LPLONG offset)
+static void AVIFILE_SamplesToBlock(const IAVIStreamImpl *This, LPLONG pos, LPLONG offset)
 {
   LONG block;
 
@@ -2317,7 +2316,7 @@ static HRESULT AVIFILE_SaveFile(IAVIFileImpl *This)
   return AVIERR_OK;
 }
 
-static HRESULT AVIFILE_SaveIndex(IAVIFileImpl *This)
+static HRESULT AVIFILE_SaveIndex(const IAVIFileImpl *This)
 {
   IAVIStreamImpl *pStream;
   AVIINDEXENTRY   idx;
@@ -2447,7 +2446,7 @@ static HRESULT AVIFILE_SaveIndex(IAVIFileImpl *This)
   return AVIERR_OK;
 }
 
-static ULONG  AVIFILE_SearchStream(IAVIFileImpl *This, DWORD fcc, LONG lSkip)
+static ULONG  AVIFILE_SearchStream(const IAVIFileImpl *This, DWORD fcc, LONG lSkip)
 {
   UINT i;
   UINT nStream;
diff --git a/reactos/dll/win32/avifil32/avifile_private.h b/reactos/dll/win32/avifil32/avifile_private.h
index 5223970db56..2f46bf0cff3 100644
--- a/reactos/dll/win32/avifil32/avifile_private.h
+++ b/reactos/dll/win32/avifil32/avifile_private.h
@@ -67,7 +67,7 @@ extern HRESULT AVIFILE_CreateACMStream(REFIID riid, LPVOID *ppobj);
 extern HRESULT AVIFILE_CreateICMStream(REFIID riid, LPVOID *ppobj);
 extern PAVIEDITSTREAM AVIFILE_CreateEditStream(PAVISTREAM pstream);
 extern PGETFRAME AVIFILE_CreateGetFrame(PAVISTREAM pstream);
-extern PAVIFILE  AVIFILE_CreateAVITempFile(int nStreams,PAVISTREAM *ppStreams);
+extern PAVIFILE  AVIFILE_CreateAVITempFile(int nStreams, const PAVISTREAM *ppStreams);
 
 extern LPCWSTR  AVIFILE_BasenameW(LPCWSTR szFileName);
 
diff --git a/reactos/dll/win32/avifil32/editstream.c b/reactos/dll/win32/avifil32/editstream.c
index d275390443b..14d361e2a32 100644
--- a/reactos/dll/win32/avifil32/editstream.c
+++ b/reactos/dll/win32/avifil32/editstream.c
@@ -23,7 +23,6 @@
 #include "winbase.h"
 #include "winuser.h"
 #include "wingdi.h"
-#include "winnls.h"
 #include "winerror.h"
 #include "mmsystem.h"
 #include "vfw.h"
diff --git a/reactos/dll/win32/avifil32/extrachunk.c b/reactos/dll/win32/avifil32/extrachunk.c
index 8fad124220c..45096e877a2 100644
--- a/reactos/dll/win32/avifil32/extrachunk.c
+++ b/reactos/dll/win32/avifil32/extrachunk.c
@@ -29,7 +29,7 @@
 WINE_DEFAULT_DEBUG_CHANNEL(avifile);
 
 /* reads a chunk outof the extrachunk-structure */
-HRESULT ReadExtraChunk(const LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lpData,LPLONG size)
+HRESULT ReadExtraChunk(const EXTRACHUNKS *extra,FOURCC ckid,LPVOID lpData,LPLONG size)
 {
   LPBYTE lp;
   DWORD  cb;
@@ -99,7 +99,7 @@ HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPCVOID lpData, LONG siz
 }
 
 /* reads a chunk fomr the HMMIO into the extrachunk-structure */
-HRESULT ReadChunkIntoExtra(LPEXTRACHUNKS extra,HMMIO hmmio,MMCKINFO *lpck)
+HRESULT ReadChunkIntoExtra(LPEXTRACHUNKS extra,HMMIO hmmio,const MMCKINFO *lpck)
 {
   LPDWORD lp;
   DWORD   cb;
diff --git a/reactos/dll/win32/avifil32/extrachunk.h b/reactos/dll/win32/avifil32/extrachunk.h
index 981f68e5f5a..3e097ba09c4 100644
--- a/reactos/dll/win32/avifil32/extrachunk.h
+++ b/reactos/dll/win32/avifil32/extrachunk.h
@@ -35,13 +35,13 @@ typedef struct _EXTRACHUNKS {
 } EXTRACHUNKS, *LPEXTRACHUNKS;
 
 /* reads a chunk outof the extrachunk-structure */
-HRESULT ReadExtraChunk(const LPEXTRACHUNKS extra,FOURCC ckid,LPVOID lp,LPLONG size);
+HRESULT ReadExtraChunk(const EXTRACHUNKS *extra,FOURCC ckid,LPVOID lp,LPLONG size);
 
 /* writes a chunk into the extrachunk-structure */
 HRESULT WriteExtraChunk(LPEXTRACHUNKS extra,FOURCC ckid,LPCVOID lp,LONG size);
 
 /* reads a chunk fomr the HMMIO into the extrachunk-structure */
-HRESULT ReadChunkIntoExtra(LPEXTRACHUNKS extra,HMMIO hmmio,MMCKINFO *lpck);
+HRESULT ReadChunkIntoExtra(LPEXTRACHUNKS extra,HMMIO hmmio,const MMCKINFO *lpck);
 
 /* reads all non-junk chunks into the extrachunk-structure until it finds
  * the given chunk or the optional parent-chunk is at the end */
diff --git a/reactos/dll/win32/avifil32/factory.c b/reactos/dll/win32/avifil32/factory.c
index 8b0faacc656..ae717c879e1 100644
--- a/reactos/dll/win32/avifil32/factory.c
+++ b/reactos/dll/win32/avifil32/factory.c
@@ -16,7 +16,6 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
-#include <assert.h>
 #include <stdarg.h>
 
 #define COBJMACROS
@@ -25,7 +24,6 @@
 #include "winbase.h"
 #include "wingdi.h"
 #include "winuser.h"
-#include "winnls.h"
 #include "winerror.h"
 
 #include "ole2.h"
diff --git a/reactos/dll/win32/avifil32/getframe.c b/reactos/dll/win32/avifil32/getframe.c
index 558ff4aa27e..d342b1255ae 100644
--- a/reactos/dll/win32/avifil32/getframe.c
+++ b/reactos/dll/win32/avifil32/getframe.c
@@ -16,12 +16,10 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
-#include <assert.h>
 #include <stdarg.h>
 
 #include "windef.h"
 #include "winbase.h"
-#include "winnls.h"
 #include "wingdi.h"
 #include "winuser.h"
 #include "vfw.h"
diff --git a/reactos/dll/win32/avifil32/icmstream.c b/reactos/dll/win32/avifil32/icmstream.c
index 5e9af16defa..82536052d15 100644
--- a/reactos/dll/win32/avifil32/icmstream.c
+++ b/reactos/dll/win32/avifil32/icmstream.c
@@ -23,11 +23,9 @@
 #include "winbase.h"
 #include "wingdi.h"
 #include "winuser.h"
-#include "winnls.h"
 #include "winerror.h"
 #include "mmsystem.h"
 #include "vfw.h"
-#include "msacm.h"
 
 #include "avifile_private.h"
 
diff --git a/reactos/dll/win32/avifil32/regsvr.c b/reactos/dll/win32/avifil32/regsvr.c
index ce811518aec..c98de1b81e7 100644
--- a/reactos/dll/win32/avifil32/regsvr.c
+++ b/reactos/dll/win32/avifil32/regsvr.c
@@ -28,7 +28,6 @@
 #include "winreg.h"
 #include "winerror.h"
 
-#include "mmsystem.h"
 #include "vfw.h"
 #include "avifile_private.h"
 
diff --git a/reactos/dll/win32/avifil32/tmpfile.c b/reactos/dll/win32/avifil32/tmpfile.c
index 2dfcc95b6d4..27d9e4f9b25 100644
--- a/reactos/dll/win32/avifil32/tmpfile.c
+++ b/reactos/dll/win32/avifil32/tmpfile.c
@@ -16,16 +16,13 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */
 
-#include <assert.h>
 #include <stdarg.h>
 
 #include "windef.h"
 #include "winbase.h"
 #include "wingdi.h"
 #include "winuser.h"
-#include "winnls.h"
 #include "winerror.h"
-#include "mmsystem.h"
 #include "vfw.h"
 
 #include "avifile_private.h"
@@ -71,7 +68,7 @@ typedef struct _ITmpFileImpl {
   PAVISTREAM   *ppStreams;
 } ITmpFileImpl;
 
-PAVIFILE AVIFILE_CreateAVITempFile(int nStreams, PAVISTREAM *ppStreams) {
+PAVIFILE AVIFILE_CreateAVITempFile(int nStreams, const PAVISTREAM *ppStreams) {
   ITmpFileImpl *tmpFile;
   int           i;
 
diff --git a/reactos/dll/win32/avifil32/wavfile.c b/reactos/dll/win32/avifil32/wavfile.c
index e2f82fe0300..d3048d60318 100644
--- a/reactos/dll/win32/avifil32/wavfile.c
+++ b/reactos/dll/win32/avifil32/wavfile.c
@@ -212,7 +212,7 @@ struct _IAVIFileImpl {
 
 static HRESULT AVIFILE_LoadFile(IAVIFileImpl *This);
 static HRESULT AVIFILE_LoadSunFile(IAVIFileImpl *This);
-static HRESULT AVIFILE_SaveFile(IAVIFileImpl *This);
+static HRESULT AVIFILE_SaveFile(const IAVIFileImpl *This);
 
 HRESULT AVIFILE_CreateWAVFile(REFIID riid, LPVOID *ppv)
 {
@@ -1248,7 +1248,7 @@ static HRESULT AVIFILE_LoadSunFile(IAVIFileImpl *This)
   return AVIERR_OK;
 }
 
-static HRESULT AVIFILE_SaveFile(IAVIFileImpl *This)
+static HRESULT AVIFILE_SaveFile(const IAVIFileImpl *This)
 {
   MMCKINFO ckRIFF;
   MMCKINFO ck;