diff --git a/script/start-local-collaboration b/script/start-local-collaboration
index 4371969580..9c63b301e5 100755
--- a/script/start-local-collaboration
+++ b/script/start-local-collaboration
@@ -25,9 +25,13 @@ if [[ $username_1 == $username_2 ]]; then
 fi
 
 # Make each Zed instance take up half of the screen.
-screen_size=($(system_profiler SPDisplaysDataType | grep Resolution | head -n1 | egrep -o '[0-9]+'))
-width=$(expr ${screen_size[0]} / 2)
-height=${screen_size[1]}
+resolution_line=$(system_profiler SPDisplaysDataType | grep Resolution | head -n1)
+screen_size=($(echo $resolution_line | egrep -o '[0-9]+'))
+scale_factor=1
+if [[ $resolution_line =~ Retina ]]; then scale_factor=2; fi
+width=$(expr ${screen_size[0]} / 2 / $scale_factor)
+height=${screen_size[1] / $scale_factor}
+
 position_1=0,0
 position_2=${width},0
 
@@ -37,12 +41,10 @@ export ZED_SERVER_URL=http://localhost:8080
 export ZED_WINDOW_SIZE=${width},${height}
 
 cargo build
-sleep 0.1
+sleep 0.5
 
 # Start the two Zed child processes. Open the given paths with the first instance.
 trap "trap - SIGTERM && kill -- -$$" SIGINT SIGTERM EXIT
 ZED_IMPERSONATE=${username_1} ZED_WINDOW_POSITION=${position_1} target/debug/Zed $@ &
-sleep 0.1
 ZED_IMPERSONATE=${username_2} ZED_WINDOW_POSITION=${position_2} target/debug/Zed &
-sleep 0.1
 wait