diff --git a/mozilla/extensions/pref/autoconfig/src/beos/platform.js b/mozilla/extensions/pref/autoconfig/src/beos/platform.js
new file mode 100644
index 00000000000..2acc49d2470
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/beos/platform.js
@@ -0,0 +1,2 @@
+// BeOS specific auto configuration preference defaults
+platform.value = "beos";
diff --git a/mozilla/extensions/pref/autoconfig/src/mac/MANIFEST b/mozilla/extensions/pref/autoconfig/src/mac/MANIFEST
new file mode 100644
index 00000000000..57bad20ed1f
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/mac/MANIFEST
@@ -0,0 +1 @@
+platform.js
diff --git a/mozilla/extensions/pref/autoconfig/src/mac/platform.js b/mozilla/extensions/pref/autoconfig/src/mac/platform.js
new file mode 100644
index 00000000000..6a4d762dd3a
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/mac/platform.js
@@ -0,0 +1,2 @@
+// Mac specific auto configuration preference defaults
+platform.value = "macintosh";
diff --git a/mozilla/extensions/pref/autoconfig/src/os2/platform.js b/mozilla/extensions/pref/autoconfig/src/os2/platform.js
new file mode 100644
index 00000000000..bb65f0815da
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/os2/platform.js
@@ -0,0 +1,2 @@
+// OS2 specific auto configuration preference defaults
+platform.value = "windows";
diff --git a/mozilla/extensions/pref/autoconfig/src/unix/platform.js b/mozilla/extensions/pref/autoconfig/src/unix/platform.js
new file mode 100644
index 00000000000..8cc65b49050
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/unix/platform.js
@@ -0,0 +1,2 @@
+// Unix specific auto configuration preference defaults
+platform.value = "unix";
diff --git a/mozilla/extensions/pref/autoconfig/src/win/platform.js b/mozilla/extensions/pref/autoconfig/src/win/platform.js
new file mode 100644
index 00000000000..c2d7a2fce9b
--- /dev/null
+++ b/mozilla/extensions/pref/autoconfig/src/win/platform.js
@@ -0,0 +1,2 @@
+// Windows specific auto configuration preference defaults
+platform.value = "windows";