diff --git a/contrib/build-osx/make_osx b/contrib/build-osx/make_osx
index e2bc2bf64..32172b635 100755
--- a/contrib/build-osx/make_osx
+++ b/contrib/build-osx/make_osx
@@ -88,7 +88,7 @@ for d in ~/Library/Python/ ~/.pyenv .; do
 done
 
 info "Building binary"
-pyinstaller --noconfirm --ascii --name $VERSION contrib/build-osx/osx.spec || fail "Could not build binary"
+pyinstaller --noconfirm --ascii --clean --name $VERSION contrib/build-osx/osx.spec || fail "Could not build binary"
 
 info "Creating .DMG"
 hdiutil create -fs HFS+ -volname $PACKAGE -srcfolder dist/$PACKAGE.app dist/electrum-$VERSION.dmg || fail "Could not create .DMG"
diff --git a/contrib/build-wine/build-electrum-git.sh b/contrib/build-wine/build-electrum-git.sh
index aec6aa846..2b5eea0cd 100755
--- a/contrib/build-wine/build-electrum-git.sh
+++ b/contrib/build-wine/build-electrum-git.sh
@@ -75,7 +75,7 @@ cd ..
 rm -rf dist/
 
 # build standalone and portable versions
-wine "C:/python$PYTHON_VERSION/scripts/pyinstaller.exe" --noconfirm --ascii --name $NAME_ROOT-$VERSION -w deterministic.spec
+wine "C:/python$PYTHON_VERSION/scripts/pyinstaller.exe" --noconfirm --ascii --clean --name $NAME_ROOT-$VERSION -w deterministic.spec
 
 # set timestamps in dist, in order to make the installer reproducible
 pushd dist