Index: os/macosx/plistgen.sh
===================================================================
--- os/macosx/plistgen.sh	(revision 22139)
+++ os/macosx/plistgen.sh	(working copy)
@@ -44,5 +44,14 @@
         <string>Copyright 2004-$date The OpenTTD team</string>
         <key>NSPrincipalClass</key>
         <string>NSApplication</string>
+        <key>LSMinimumSystemVersionByArchitecture</key>
+        <dict>
+            <key>i386</key>
+            <string>10.4.0</string>
+            <key>x86_64</key>
+            <string>10.6.0</string>
+            <key>ppc</key>
+            <string>10.4.0</string>
+        </dict>
 </dict>
 </plist>" > "$1"/Contents/Info.plist