diff --git a/toolkit/mozapps/extensions/XPIProvider.jsm b/toolkit/mozapps/extensions/XPIProvider.jsm
index 7981ad6f780..cd8224c2b5c 100644
--- a/toolkit/mozapps/extensions/XPIProvider.jsm
+++ b/toolkit/mozapps/extensions/XPIProvider.jsm
@@ -4334,7 +4334,8 @@ AddonInstall.prototype = {
   cancel: function AI_cancel() {
     switch (this.state) {
     case AddonManager.STATE_DOWNLOADING:
-      this.channel.cancel(Cr.NS_BINDING_ABORTED);
+      if (this.channel)
+        this.channel.cancel(Cr.NS_BINDING_ABORTED);
     case AddonManager.STATE_AVAILABLE:
     case AddonManager.STATE_DOWNLOADED:
       LOG("Cancelling download of " + this.sourceURI.spec);
@@ -4636,6 +4637,10 @@ AddonInstall.prototype = {
       return;
     }
 
+    // If a listener changed our state then do not proceed with the download
+    if (this.state != AddonManager.STATE_DOWNLOADING)
+      return;
+
     try {
       this.file = getTemporaryFile();
       this.ownsTempFile = true;
@@ -4872,6 +4877,10 @@ AddonInstall.prototype = {
       if (AddonManagerPrivate.callInstallListeners("onDownloadEnded",
                                                    self.listeners,
                                                    self.wrapper)) {
+        // If a listener changed our state then do not proceed with the install
+        if (self.state != AddonManager.STATE_DOWNLOADED)
+          return;
+
         self.install();
 
         if (self.linkedInstalls) {
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_install.js b/toolkit/mozapps/extensions/test/xpcshell/test_install.js
index 9b0a450b22c..8739bbbf8c4 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_install.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_install.js
@@ -947,7 +947,93 @@ function check_test_13(install) {
     AddonManager.getAddonByID("addon2@tests.mozilla.org", function(a2) {
       do_check_eq(a2.version, "2.0");
 
-      end_test();
+      run_test_14();
     });
   });
 }
+
+// Check that cancelling the install from onDownloadStarted actually cancels it
+function run_test_14() {
+  prepare_test({ }, [
+    "onNewInstall"
+  ]);
+
+  let url = "http://localhost:4444/addons/test_install2_1.xpi";
+  AddonManager.getInstallForURL(url, function(install) {
+    ensure_test_completed();
+
+    do_check_eq(install.file, null);
+
+    prepare_test({ }, [
+      "onDownloadStarted"
+    ], check_test_14);
+    install.install();
+  }, "application/x-xpinstall");
+}
+
+function check_test_14(install) {
+  prepare_test({ }, [
+    "onDownloadCancelled"
+  ]);
+
+  install.cancel();
+
+  ensure_test_completed();
+
+  install.addListener({
+    onDownloadProgress: function() {
+      do_throw("Download should not have continued");
+    },
+    onDownloadEnded: function() {
+      do_throw("Download should not have continued");
+    }
+  });
+
+  // Allow the listener to return to see if it continues downloading. The
+  // The listener only really tests if we give it time to see progress, the
+  // file check isn't ideal either
+  do_execute_soon(function() {
+    do_check_eq(install.file, null);
+
+    run_test_15();
+  });
+}
+
+// Checks that cancelling the install from onDownloadEnded actually cancels it
+function run_test_15() {
+  prepare_test({ }, [
+    "onNewInstall"
+  ]);
+
+  let url = "http://localhost:4444/addons/test_install2_1.xpi";
+  AddonManager.getInstallForURL(url, function(install) {
+    ensure_test_completed();
+
+    do_check_eq(install.file, null);
+
+    prepare_test({ }, [
+      "onDownloadStarted",
+      "onDownloadEnded"
+    ], check_test_15);
+    install.install();
+  }, "application/x-xpinstall");
+}
+
+function check_test_15(install) {
+  prepare_test({ }, [
+    "onDownloadCancelled"
+  ]);
+
+  install.cancel();
+
+  ensure_test_completed();
+
+  install.addListener({
+    onInstallStarted: function() {
+      do_throw("Install should not have continued");
+    }
+  });
+
+  // Allow the listener to return to see if it starts installing
+  do_execute_soon(end_test);
+}