diff --git a/dlls/dwrite/gdiinterop.c b/dlls/dwrite/gdiinterop.c
index 2fec7e9fff1..5b542d93e32 100644
--- a/dlls/dwrite/gdiinterop.c
+++ b/dlls/dwrite/gdiinterop.c
@@ -758,7 +758,7 @@ struct font_fileinfo
 /* Undocumented gdi32 exports, used to access actually selected font information */
 extern BOOL WINAPI GetFontRealizationInfo(HDC hdc, struct font_realization_info *info);
 extern BOOL WINAPI GetFontFileInfo(DWORD instance_id, DWORD file_index, struct font_fileinfo *info, SIZE_T size, SIZE_T *needed);
-extern BOOL WINAPI GetFontFileData(DWORD instance_id, DWORD file_index, UINT64 offset, void *buff, DWORD buff_size);
+extern BOOL WINAPI GetFontFileData(DWORD instance_id, DWORD file_index, UINT64 offset, void *buff, SIZE_T buff_size);
 
 static HRESULT WINAPI gdiinterop_CreateFontFaceFromHdc(IDWriteGdiInterop1 *iface,
     HDC hdc, IDWriteFontFace **fontface)
diff --git a/dlls/gdi32/tests/font.c b/dlls/gdi32/tests/font.c
index 82cec09e982..711c9ca4a32 100644
--- a/dlls/gdi32/tests/font.c
+++ b/dlls/gdi32/tests/font.c
@@ -46,7 +46,7 @@ static BOOL  (WINAPI *pGetCharWidthInfo)(HDC hdc, void *);
 static BOOL  (WINAPI *pGdiRealizationInfo)(HDC hdc, DWORD *);
 static BOOL  (WINAPI *pGetFontRealizationInfo)(HDC hdc, DWORD *);
 static BOOL  (WINAPI *pGetFontFileInfo)(DWORD, DWORD, void *, SIZE_T, SIZE_T *);
-static BOOL  (WINAPI *pGetFontFileData)(DWORD, DWORD, UINT64, void *, DWORD);
+static BOOL  (WINAPI *pGetFontFileData)(DWORD, DWORD, UINT64, void *, SIZE_T);
 
 static HMODULE hgdi32 = 0;
 static const MAT2 mat = { {0,1}, {0,0}, {0,0}, {0,1} };
diff --git a/dlls/gdi32/text.c b/dlls/gdi32/text.c
index 155e798bafc..b61c8ed4542 100644
--- a/dlls/gdi32/text.c
+++ b/dlls/gdi32/text.c
@@ -2015,7 +2015,7 @@ BOOL WINAPI EnableEUDC( BOOL enable )
  *             GetFontFileData   (GDI32.@)
  */
 BOOL WINAPI GetFontFileData( DWORD instance_id, DWORD file_index, UINT64 offset,
-                             void *buff, DWORD buff_size )
+                             void *buff, SIZE_T buff_size )
 {
     return NtGdiGetFontFileData( instance_id, file_index, &offset, buff, buff_size );
 }
diff --git a/dlls/win32u/font.c b/dlls/win32u/font.c
index 4a341453012..c21d87c1fbc 100644
--- a/dlls/win32u/font.c
+++ b/dlls/win32u/font.c
@@ -7008,7 +7008,7 @@ BOOL WINAPI NtGdiGetRasterizerCaps( RASTERIZER_STATUS *status, UINT size )
  *             NtGdiGetFontFileData   (win32u.@)
  */
 BOOL WINAPI NtGdiGetFontFileData( DWORD instance_id, DWORD file_index, UINT64 *offset,
-                                  void *buff, DWORD buff_size )
+                                  void *buff, SIZE_T buff_size )
 {
     struct gdi_font *font;
     DWORD tag = 0, size;
diff --git a/dlls/wow64win/gdi.c b/dlls/wow64win/gdi.c
index c846e47ba5e..1bcfd17cdfb 100644
--- a/dlls/wow64win/gdi.c
+++ b/dlls/wow64win/gdi.c
@@ -1136,7 +1136,7 @@ NTSTATUS WINAPI wow64_NtGdiGetFontFileData( UINT *args )
     DWORD file_index = get_ulong( &args );
     UINT64 *offset = get_ptr( &args );
     void *buff = get_ptr( &args );
-    DWORD buff_size = get_ulong( &args );
+    SIZE_T buff_size = get_ulong( &args );
 
     return NtGdiGetFontFileData( instance_id, file_index, offset, buff, buff_size );
 }
diff --git a/include/ntgdi.h b/include/ntgdi.h
index 55c6739a54f..f93708d5400 100644
--- a/include/ntgdi.h
+++ b/include/ntgdi.h
@@ -341,7 +341,7 @@ INT      WINAPI NtGdiGetDeviceCaps( HDC hdc, INT cap );
 BOOL     WINAPI NtGdiGetDeviceGammaRamp( HDC hdc, void *ptr );
 DWORD    WINAPI NtGdiGetFontData( HDC hdc, DWORD table, DWORD offset, void *buffer, DWORD length );
 BOOL     WINAPI NtGdiGetFontFileData( DWORD instance_id, DWORD file_index, UINT64 *offset,
-                                      void *buff, DWORD buff_size );
+                                      void *buff, SIZE_T buff_size );
 BOOL     WINAPI NtGdiGetFontFileInfo( DWORD instance_id, DWORD file_index, struct font_fileinfo *info,
                                       SIZE_T size, SIZE_T *needed );
 DWORD    WINAPI NtGdiGetFontUnicodeRanges( HDC hdc, GLYPHSET *lpgs );