diff --git a/toolkit/mozapps/update/test/unit/head_update.js.in b/toolkit/mozapps/update/test/unit/head_update.js.in
index bdecd3399c12..915a798fb09f 100644
--- a/toolkit/mozapps/update/test/unit/head_update.js.in
+++ b/toolkit/mozapps/update/test/unit/head_update.js.in
@@ -470,6 +470,83 @@ if (IS_WIN) {
   }
 }
 
+/**
+ * Copies a directory and its children. First it tries nsIFile::CopyTo on the
+ * source directory and if that fails it will fall back to recursing.
+ *
+ * @param  aSrcDir
+ *         nsIFile for the source directory to be copied from.
+ * @param  aDestDir
+ *         nsIFile for the destination directory parent.
+ * @param  aDestLeafName
+ *         the destination directory name.
+ */
+function copyDirRecursive(aSrcDir, aDestDir, aDestLeafName) {
+  try {
+    aSrcDir.copyTo(aDestDir, aDestLeafName);
+    return;
+  }
+  catch (e) {
+    logTestInfo("copyTo error - src path: " + aSrcDir.path + ", dest path: " +
+                aDestDir.path + ", dir name: " + aDestLeafName +
+                ", exception: " + e);
+  }
+
+  let destDir = aDestDir.clone();
+  destDir.append(aDestLeafName);
+  if (!destDir.exists()) {
+    try {
+      destDir.create(AUS_Ci.nsIFile.DIRECTORY_TYPE, PERMS_DIRECTORY);
+    }
+    catch (e) {
+      logTestInfo("unable to create directory, path: " + destDir.path +
+                  ", exception: " + e);
+      do_throw(e);
+    }
+  }
+  var dirEntries = aSrcDir.directoryEntries;
+  while (dirEntries.hasMoreElements()) {
+    let entry = dirEntries.getNext().QueryInterface(AUS_Ci.nsIFile);
+
+    if (entry.isDirectory()) {
+      copyDirRecursive(entry, destDir, entry.leafName);
+    }
+    else {
+      let destFile = destDir.clone();
+      destFile.append(entry.leafName);
+      if (destFile.exists()) {
+        try {
+          destFile.remove(false);
+        }
+        catch (e) {
+          logTestInfo("unable to remove file, path: " + destFile.path +
+                      ", exception: " + e);
+          let bakFile = destDir.clone();
+          bakFile.append(entry.leafName + ".bak");
+          logTestInfo("attempting moveTo of file, src path: " + destFile.path +
+                      ", dest path: " + bakFile.path + ", exception: " + e);
+          try {
+            destFile.moveTo(destDir, bakFile.leafName);
+          }
+          catch (e) {
+            logTestInfo("unable to move file, src path: " + destFile.path +
+                        ", dest path: " + bakFile.path + ", exception: " + e);
+            do_throw(e);
+          }
+        }
+      }
+      try {
+        entry.copyTo(destDir, entry.leafName);
+      }
+      catch (e) {
+        logTestInfo("unable to copy file, src path: " + entry.path +
+                    ", dest path: " + destFile.path + ", exception: " + e);
+        do_throw(e);
+      }
+    }
+  }
+}
+
 /**
  * Helper function for updater tests for launching the updater binary to apply
  * a mar file.
diff --git a/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js b/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
index e8b3db8716fb..a96e305ff93b 100644
--- a/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
+++ b/toolkit/mozapps/update/test/unit/test_0201_app_launch_apply_update.js
@@ -303,7 +303,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;
diff --git a/toolkit/mozapps/update/test/unit/test_0202_app_launch_apply_update_dirlocked.js b/toolkit/mozapps/update/test/unit/test_0202_app_launch_apply_update_dirlocked.js
index 9ac1b6618aca..cc12b847e087 100644
--- a/toolkit/mozapps/update/test/unit/test_0202_app_launch_apply_update_dirlocked.js
+++ b/toolkit/mozapps/update/test/unit/test_0202_app_launch_apply_update_dirlocked.js
@@ -238,7 +238,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;
diff --git a/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js b/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
index d2424af2cf64..c655ceef3ab5 100644
--- a/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
+++ b/toolkit/mozapps/update/test/unit/test_0203_app_launch_apply_update.js
@@ -332,7 +332,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
index b3ac0a8b6b24..a1eb4f4597a9 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0201_app_launch_apply_update_svc.js
@@ -309,7 +309,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
index f165f357bb68..ec03a3807d52 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0202_app_launch_apply_update_dirlocked_svc.js
@@ -247,7 +247,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;
diff --git a/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js b/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
index fca5aef3d4e6..4d77c41ebb3b 100644
--- a/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
+++ b/toolkit/mozapps/update/test_svc/unit/test_0203_app_launch_apply_update_svc.js
@@ -335,7 +335,7 @@ function adjustPathsOnWindows() {
   tmpDir.append("ExecutableDir.tmp");
   tmpDir.createUnique(tmpDir.DIRECTORY_TYPE, 0755);
   let procDir = getCurrentProcessDir();
-  procDir.copyTo(tmpDir, "bin");
+  copyDirRecursive(procDir, tmpDir, "bin");
   let newDir = tmpDir.clone();
   newDir.append("bin");
   gWindowsBinDir = newDir;