diff --git a/resources/scripts/.appveyor-build-win.ps1 b/resources/scripts/.appveyor-build-win.ps1
index 42aaf22a7..fb3c30016 100644
--- a/resources/scripts/.appveyor-build-win.ps1
+++ b/resources/scripts/.appveyor-build-win.ps1
@@ -29,7 +29,8 @@ Invoke-WebRequest -Uri $qtbase_url -OutFile $output
 & "..\resources\scripts\7za\7za.exe" x $output
 
 $qt_mysql_dir = ".\qtbase-everywhere-src-5.14.2\src\plugins\sqldrivers"
-qmake.exe "MYSQL_INCDIR=`"$mysql_dir/include`" MYSQL_LIBDIR=`"$mysql_dir/lib`"" "$qt_mysql_dir\sqldrivers.pro"
+$mysql_d_rev = $mmysql_dir.Replace('\', '/')
+qmake.exe "MYSQL_INCDIR=`"$mysql_d_rev/include`" MYSQL_LIBDIR=`"$mysql_d_rev/lib`"" "$qt_mysql_dir\sqldrivers.pro"
 
 nmake.exe sub-mysql
 ls