diff --git a/reactos/dll/win32/shell32/shellord.cpp b/reactos/dll/win32/shell32/shellord.cpp
index 629e1f832cd..6d19541fb11 100644
--- a/reactos/dll/win32/shell32/shellord.cpp
+++ b/reactos/dll/win32/shell32/shellord.cpp
@@ -309,7 +309,7 @@ BOOL WINAPI RegisterShellHook(
  * ordinal. If you change the implementation here please update the code in
  * shlwapi as well.
  */
-EXTERN_C int WINAPI ShellMessageBoxW(
+EXTERN_C int ShellMessageBoxW(
     HINSTANCE hInstance,
     HWND hWnd,
     LPCWSTR lpText,
@@ -367,7 +367,7 @@ EXTERN_C int WINAPI ShellMessageBoxW(
  * NOTES
  *     Exported by ordinal
  */
-EXTERN_C int WINAPI ShellMessageBoxA(
+EXTERN_C int ShellMessageBoxA(
     HINSTANCE hInstance,
     HWND hWnd,
     LPCSTR lpText,
diff --git a/reactos/include/psdk/shellapi.h b/reactos/include/psdk/shellapi.h
index b4c2c13d73e..a116c918b95 100644
--- a/reactos/include/psdk/shellapi.h
+++ b/reactos/include/psdk/shellapi.h
@@ -476,7 +476,6 @@ ShellAboutW(
   _In_opt_ HICON hIcon);
 
 int
-WINAPI
 ShellMessageBoxA(
   _In_opt_ HINSTANCE hAppInst,
   _In_opt_ HWND hWnd,
@@ -486,7 +485,6 @@ ShellMessageBoxA(
   ...);
 
 int
-WINAPI
 ShellMessageBoxW(
   _In_opt_ HINSTANCE hAppInst,
   _In_opt_ HWND hWnd,