diff --git a/synapse/install.sh b/synapse/install.sh
index c83ca6512a..2cc68dee03 100755
--- a/synapse/install.sh
+++ b/synapse/install.sh
@@ -45,11 +45,10 @@ cp -r $BASE_DIR/config-templates/$CONFIG_TEMPLATE/. ./
 
 # Hashes used instead of slashes because we'll get a value back from $(pwd) that'll be
 # full of un-escapable slashes.
-# Manually directing output to .templated file and then manually renaming back on top
-# of the original file because -i is a nonstandard sed feature which is implemented 
-# differently, across os X and ubuntu at least
-sed "s#{{SYNAPSE_ROOT}}#$(pwd)/#g" homeserver.yaml > homeserver.yaml.templated && mv homeserver.yaml.templated homeserver.yaml
-sed "s#{{SYNAPSE_PORT}}#${PORT}#g" homeserver.yaml > homeserver.yaml.templated && mv homeserver.yaml.templated homeserver.yaml
-sed "s#{{FORM_SECRET}}#$(uuidgen)#g" homeserver.yaml > homeserver.yaml.templated && mv homeserver.yaml.templated homeserver.yaml
-sed "s#{{REGISTRATION_SHARED_SECRET}}#$(uuidgen)#g" homeserver.yaml > homeserver.yaml.templated && mv homeserver.yaml.templated homeserver.yaml
-sed "s#{{MACAROON_SECRET_KEY}}#$(uuidgen)#g" homeserver.yaml > homeserver.yaml.templated && mv homeserver.yaml.templated homeserver.yaml
+# Use .bak suffix as using no suffix doesn't work macOS.
+sed -i.bak "s#{{SYNAPSE_ROOT}}#$(pwd)/#g" homeserver.yaml
+sed -i.bak "s#{{SYNAPSE_PORT}}#${PORT}#g" homeserver.yaml
+sed -i.bak "s#{{FORM_SECRET}}#$(uuidgen)#g" homeserver.yaml
+sed -i.bak "s#{{REGISTRATION_SHARED_SECRET}}#$(uuidgen)#g" homeserver.yaml
+sed -i.bak "s#{{MACAROON_SECRET_KEY}}#$(uuidgen)#g" homeserver.yaml
+rm *.bak