diff --git a/netwerk/protocol/res/SubstitutingProtocolHandler.cpp b/netwerk/protocol/res/SubstitutingProtocolHandler.cpp
index e844ce919351..9dabcc36be68 100644
--- a/netwerk/protocol/res/SubstitutingProtocolHandler.cpp
+++ b/netwerk/protocol/res/SubstitutingProtocolHandler.cpp
@@ -425,19 +425,7 @@ SubstitutingProtocolHandler::ResolveURI(nsIURI *uri, nsACString &result)
     rv = baseURI->GetSpec(result);
   } else {
     // Make sure we always resolve the path as file-relative to our target URI.
-    // When the baseURI doesn't end with a /, a file-relative resolution is going
-    // to pick something in the parent directory, so we resolve using an absolute
-    // path derived from the full path of the baseURI in that case.
-    nsAutoCString basePath;
-    rv = baseURI->GetFilePath(basePath);
-    if (NS_SUCCEEDED(rv) && !StringEndsWith(basePath, NS_LITERAL_CSTRING("/"))) {
-      // Cf. the assertion above, path already starts with a /, so prefixing
-      // with a string that doesn't end with one will leave us wit the right
-      // amount of /.
-      path.Insert(basePath, 0);
-    } else {
-      path.Insert('.', 0);
-    }
+    path.Insert('.', 0);
     rv = baseURI->Resolve(path, result);
   }
 
diff --git a/netwerk/test/unit/test_bug337744.js b/netwerk/test/unit/test_bug337744.js
index a92e09b609d6..b100f68438b8 100644
--- a/netwerk/test/unit/test_bug337744.js
+++ b/netwerk/test/unit/test_bug337744.js
@@ -94,15 +94,9 @@ function run_test() {
   let rootFile = Services.dirsvc.get("GreD", Ci.nsIFile);
   let rootURI = Services.io.newFileURI(rootFile);
 
-  let inexistentFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
-  inexistentFile.initWithPath("/this/directory/does/not/exist");
-  let inexistentURI = Services.io.newFileURI(inexistentFile);
-
   resProto.setSubstitution("res-test", rootURI);
-  resProto.setSubstitution("res-inexistent", inexistentURI);
   do_register_cleanup(() => {
     resProto.setSubstitution("res-test", null);
-    resProto.setSubstitution("res-inexistent", null);
   });
 
   let baseRoot = resProto.resolveURI(Services.io.newURI("resource:///"));
@@ -110,7 +104,6 @@ function run_test() {
 
   for (var spec of specs) {
     check_safe_resolution(spec, rootURI.spec);
-    check_safe_resolution(spec.replace("res-test", "res-inexistent"), inexistentURI.spec);
     check_safe_resolution(spec.replace("res-test", ""), baseRoot);
     check_safe_resolution(spec.replace("res-test", "gre"), greRoot);
   }