diff --git a/dlls/kernel32/virtual.c b/dlls/kernel32/virtual.c
index 4bfc6cc76d9..cce707bb95c 100644
--- a/dlls/kernel32/virtual.c
+++ b/dlls/kernel32/virtual.c
@@ -647,7 +647,7 @@ UINT WINAPI ResetWriteWatch( LPVOID base, SIZE_T size )
  *  Success: TRUE.
  *	Failure: FALSE. Process has read access to entire block.
  */
-BOOL WINAPI IsBadReadPtr( LPCVOID ptr, UINT size )
+BOOL WINAPI IsBadReadPtr( LPCVOID ptr, UINT_PTR size )
 {
     if (!size) return FALSE;  /* handle 0 size case w/o reference */
     if (!ptr) return TRUE;
@@ -655,7 +655,7 @@ BOOL WINAPI IsBadReadPtr( LPCVOID ptr, UINT size )
     {
         volatile const char *p = ptr;
         char dummy __attribute__((unused));
-        UINT count = size;
+        UINT_PTR count = size;
 
         while (count > system_info.PageSize)
         {
@@ -689,14 +689,14 @@ BOOL WINAPI IsBadReadPtr( LPCVOID ptr, UINT size )
  *  Success: TRUE.
  *	Failure: FALSE. Process has write access to entire block.
  */
-BOOL WINAPI IsBadWritePtr( LPVOID ptr, UINT size )
+BOOL WINAPI IsBadWritePtr( LPVOID ptr, UINT_PTR size )
 {
     if (!size) return FALSE;  /* handle 0 size case w/o reference */
     if (!ptr) return TRUE;
     __TRY
     {
         volatile char *p = ptr;
-        UINT count = size;
+        UINT_PTR count = size;
 
         while (count > system_info.PageSize)
         {
@@ -730,7 +730,7 @@ BOOL WINAPI IsBadWritePtr( LPVOID ptr, UINT size )
  *  Success: TRUE.
  *	Failure: FALSE. Process has read access to entire block.
  */
-BOOL WINAPI IsBadHugeReadPtr( LPCVOID ptr, UINT size )
+BOOL WINAPI IsBadHugeReadPtr( LPCVOID ptr, UINT_PTR size )
 {
     return IsBadReadPtr( ptr, size );
 }
@@ -749,7 +749,7 @@ BOOL WINAPI IsBadHugeReadPtr( LPCVOID ptr, UINT size )
  *  Success: TRUE.
  *	Failure: FALSE. Process has write access to entire block.
  */
-BOOL WINAPI IsBadHugeWritePtr( LPVOID ptr, UINT size )
+BOOL WINAPI IsBadHugeWritePtr( LPVOID ptr, UINT_PTR size )
 {
     return IsBadWritePtr( ptr, size );
 }
@@ -786,7 +786,7 @@ BOOL WINAPI IsBadCodePtr( FARPROC ptr )
  *	Success: TRUE.
  *	Failure: FALSE. Read access to all bytes in string.
  */
-BOOL WINAPI IsBadStringPtrA( LPCSTR str, UINT max )
+BOOL WINAPI IsBadStringPtrA( LPCSTR str, UINT_PTR max )
 {
     if (!str) return TRUE;
     
@@ -810,7 +810,7 @@ BOOL WINAPI IsBadStringPtrA( LPCSTR str, UINT max )
  *
  * See IsBadStringPtrA.
  */
-BOOL WINAPI IsBadStringPtrW( LPCWSTR str, UINT max )
+BOOL WINAPI IsBadStringPtrW( LPCWSTR str, UINT_PTR max )
 {
     if (!str) return TRUE;
     
diff --git a/include/winbase.h b/include/winbase.h
index 89f27c9d393..15edac39a03 100644
--- a/include/winbase.h
+++ b/include/winbase.h
@@ -2236,13 +2236,13 @@ WINBASEAPI PSLIST_ENTRY WINAPI InterlockedFlushSList(PSLIST_HEADER);
 WINBASEAPI PSLIST_ENTRY WINAPI InterlockedPopEntrySList(PSLIST_HEADER);
 WINBASEAPI PSLIST_ENTRY WINAPI InterlockedPushEntrySList(PSLIST_HEADER, PSLIST_ENTRY);
 WINBASEAPI BOOL        WINAPI IsBadCodePtr(FARPROC);
-WINBASEAPI BOOL        WINAPI IsBadHugeReadPtr(LPCVOID,UINT);
-WINBASEAPI BOOL        WINAPI IsBadHugeWritePtr(LPVOID,UINT);
-WINBASEAPI BOOL        WINAPI IsBadReadPtr(LPCVOID,UINT);
-WINBASEAPI BOOL        WINAPI IsBadStringPtrA(LPCSTR,UINT);
-WINBASEAPI BOOL        WINAPI IsBadStringPtrW(LPCWSTR,UINT);
+WINBASEAPI BOOL        WINAPI IsBadHugeReadPtr(LPCVOID,UINT_PTR);
+WINBASEAPI BOOL        WINAPI IsBadHugeWritePtr(LPVOID,UINT_PTR);
+WINBASEAPI BOOL        WINAPI IsBadReadPtr(LPCVOID,UINT_PTR);
+WINBASEAPI BOOL        WINAPI IsBadStringPtrA(LPCSTR,UINT_PTR);
+WINBASEAPI BOOL        WINAPI IsBadStringPtrW(LPCWSTR,UINT_PTR);
 #define                       IsBadStringPtr WINELIB_NAME_AW(IsBadStringPtr)
-WINBASEAPI BOOL        WINAPI IsBadWritePtr(LPVOID,UINT);
+WINBASEAPI BOOL        WINAPI IsBadWritePtr(LPVOID,UINT_PTR);
 WINBASEAPI BOOL        WINAPI IsDebuggerPresent(void);
 WINBASEAPI BOOL        WINAPI IsSystemResumeAutomatic(void);
 WINADVAPI  BOOL        WINAPI IsTextUnicode(LPCVOID,INT,LPINT);