diff --git a/appveyor_build.cmd b/appveyor_build.cmd
index f6dc81ac3fe..2e844905212 100644
--- a/appveyor_build.cmd
+++ b/appveyor_build.cmd
@@ -154,7 +154,9 @@ if "%OCAML_PORT%" equ "" (
 )
 set LIB_EXT=
 if "%DEP_MODE%" equ "lib-ext" set LIB_EXT=^&^& make lib-ext
-"%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER %LIB_PKG% && ./configure %LIB_EXT% && make opam %POST_COMMAND%" || exit /b 1
+set PRIVATE_RUNTIME=
+if "%OCAML_PORT:~0,5%" equ "mingw" set PRIVATE_RUNTIME=--with-private-runtime
+"%CYG_ROOT%\bin\bash.exe" -lc "cd $APPVEYOR_BUILD_FOLDER %LIB_PKG% && ./configure %PRIVATE_RUNTIME% %LIB_EXT% && make opam %POST_COMMAND%" || exit /b 1
 goto :EOF
 
 :test