diff --git a/macos/make_macos_package.sh b/macos/make_macos_package.sh
index 7cdc42e0c..4dd746a7c 100755
--- a/macos/make_macos_package.sh
+++ b/macos/make_macos_package.sh
@@ -26,7 +26,7 @@ stack setup
 
 echo Building pandoc...
 stack clean
-stack install --stack-yaml=stack.pkg.yaml --local-bin-path $DEST/bin/ pandoc pandoc-citeproc
+stack install --ghc-options="-O2" --stack-yaml=stack.pkg.yaml --local-bin-path $DEST/bin/ pandoc pandoc-citeproc
 
 strip $DEST/bin/pandoc
 strip $DEST/bin/pandoc-citeproc
diff --git a/windows/make-windows-installer.bat b/windows/make-windows-installer.bat
index 1517e9bf9..15d97d9d2 100644
--- a/windows/make-windows-installer.bat
+++ b/windows/make-windows-installer.bat
@@ -1,5 +1,5 @@
 @echo off
-stack install --test --stack-yaml=..\stack.pkg.yml
+stack install --test --ghc-options="-O2" --stack-yaml=..\stack.pkg.yml
 if %errorlevel% neq 0 exit /b %errorlevel%
 for /f "delims=" %%a in ('stack path --local-bin-path') do @set BINPATH=%%a
 %BINPATH%\pandoc.exe -s --toc ..\MANUAL.txt -o MANUAL.html