diff --git a/src/drivers/win/dumper.cpp b/src/drivers/win/dumper.cpp
index 86aad87b..9529ce3d 100644
--- a/src/drivers/win/dumper.cpp
+++ b/src/drivers/win/dumper.cpp
@@ -336,7 +336,7 @@ bool DumperBnClicked(HWND hwndDlg, uint16 btnId, HWND hwndBtn)
 	return false;
 }
 
-BOOL CALLBACK DumperCallB(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
+INT_PTR CALLBACK DumperCallB(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
 	switch (uMsg)
 	{
diff --git a/src/drivers/win/dumper.h b/src/drivers/win/dumper.h
index a60c12c0..0eedaa7e 100644
--- a/src/drivers/win/dumper.h
+++ b/src/drivers/win/dumper.h
@@ -2,4 +2,4 @@
 
 #include <Windows.h>
 
-BOOL CALLBACK DumperCallB(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam);
+INT_PTR CALLBACK DumperCallB(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam);