--- a/browser/extensions/pdfjs/test/browser.ini
+++ b/browser/extensions/pdfjs/test/browser.ini
@@ -1,9 +1,12 @@
 [DEFAULT]
-skip-if = e10s # Bug 1159385
 support-files = file_pdfjs_test.pdf
 
 [browser_pdfjs_main.js]
+skip-if = e10s # Bug 1159385
 [browser_pdfjs_navigation.js]
+skip-if = e10s # Bug 1159385
 [browser_pdfjs_savedialog.js]
 [browser_pdfjs_views.js]
+skip-if = e10s # Bug 1159385
 [browser_pdfjs_zoom.js]
+skip-if = e10s # Bug 1159385

--- a/uriloader/exthandler/ExternalHelperAppParent.cpp
+++ b/uriloader/exthandler/ExternalHelperAppParent.cpp
@@ -391,17 +391,19 @@ NS_IMETHODIMP
 ExternalHelperAppParent::SetContentCharset(const nsACString& aContentCharset)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
 NS_IMETHODIMP
 ExternalHelperAppParent::GetContentDisposition(uint32_t *aContentDisposition)
 {
-  if (mContentDispositionHeader.IsEmpty())
+  // NB: mContentDisposition may or may not be set to a non UINT32_MAX value in
+  // nsExternalHelperAppService::DoContentContentProcessHelper
+  if (mContentDispositionHeader.IsEmpty() && mContentDisposition == UINT32_MAX)
     return NS_ERROR_NOT_AVAILABLE;
 
   *aContentDisposition = mContentDisposition;
   return NS_OK;
 }
 
 NS_IMETHODIMP
 ExternalHelperAppParent::SetContentDisposition(uint32_t aContentDisposition)