diff --git a/scripts/build.sh b/scripts/build.sh
index 8ad925184f5..f8853291e39 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -70,7 +70,13 @@ mkdir -p $OUTDIR/lib/streams
 cp node_modules/@openpgp/web-stream-tools/lib/*.js $OUTDIR/lib/streams
 # patch imports with .js, e.g. replace './streams' with './streams.js'
 # until https://github.com/openpgpjs/web-stream-tools/pull/20 is resolved
-sed -i.bak -E "s/'\.\/(streams|util|writer|reader|node-conversions)'/'\.\/\1\.js'/g" $OUTDIR/lib/streams/*
+STREAMS_REGEX="s/'\.\/(streams|util|writer|reader|node-conversions)'/'\.\/\1\.js'/g"
+STREAMS_FILES=$OUTDIR/lib/streams/*
+if [[ "$OSTYPE" =~ ^darwin ]]; then # macOS needs additional parameter for backup files
+  sed -i '' -E $STREAMS_REGEX $STREAMS_FILES
+else
+  sed -i -E $STREAMS_REGEX $STREAMS_FILES
+fi
 
 # to update node-forge library, which is missing the non-minified version in dist, we have to build it manually
 # cd ~/git && rm -rf ./forge && git clone https://github.com/digitalbazaar/forge.git && cd ./forge && npm install && npm run-script build