diff --git a/mozilla/modules/libjar/nsJARURI.cpp b/mozilla/modules/libjar/nsJARURI.cpp
index f4aa388f0fa..877dad58381 100644
--- a/mozilla/modules/libjar/nsJARURI.cpp
+++ b/mozilla/modules/libjar/nsJARURI.cpp
@@ -335,12 +335,27 @@ nsJARURI::Resolve(const nsACString &relativePath, nsACString &result)
     }
 
     nsCAutoString path(mJAREntry);
-    PRInt32 pos = path.RFind("/");
-    if (pos >= 0)
-        path.Truncate(pos + 1);
-    else
-        path = "";
+    PRInt32 pos = 0;
 
+    char first = relativePath.Length() > 0 ? relativePath.First() : '#';
+
+    switch (first) {
+    case '/':
+        path = "";
+        break;
+    case '?':
+    case '#':
+        pos = path.RFindChar(first);
+        if (pos >= 0)
+            path.Truncate(pos);
+        break;
+    default:
+        pos = path.RFindChar('/');
+        if (pos >= 0)
+            path.Truncate(pos + 1);
+        else
+            path = "";
+    }
     nsCAutoString resolvedEntry;
     rv = net_ResolveRelativePath(relativePath, path,
                                  resolvedEntry);
diff --git a/mozilla/netwerk/base/src/nsURLHelper.cpp b/mozilla/netwerk/base/src/nsURLHelper.cpp
index c0a2550795f..9a9bcb654d2 100644
--- a/mozilla/netwerk/base/src/nsURLHelper.cpp
+++ b/mozilla/netwerk/base/src/nsURLHelper.cpp
@@ -383,7 +383,7 @@ net_ResolveRelativePath(const nsACString &relativePath,
 
 	if ( !path.IsEmpty() ) {
 		PRUnichar last = path.Last();
-		needsDelim = !(last == '/' || last == '\\' );
+		needsDelim = !(last == '/');
 	}
 
     nsACString::const_iterator beg, end;
@@ -403,18 +403,20 @@ net_ResolveRelativePath(const nsACString &relativePath,
             stop = PR_TRUE;
             // fall through...
           case '/':
-          case '\\':
             // delimiter found
             if (name.Equals("..")) {
                 // pop path
                 // If we already have the delim at end, then
                 //  skip over that when searching for next one to the left
                 PRInt32 offset = path.Length() - (needsDelim ? 1 : 2);
+                // First check for errors
+                if (offset < 0 ) 
+                    return NS_ERROR_MALFORMED_URI;
                 PRInt32 pos = path.RFind("/", PR_FALSE, offset);
-                if (pos > 0)
+                if (pos >= 0)
                     path.Truncate(pos + 1);
                 else
-                    return NS_ERROR_MALFORMED_URI;
+                    path.Truncate();
             }
             else if (name.Equals(".") || name.Equals("")) {
                 // do nothing
diff --git a/mozilla/netwerk/protocol/jar/src/nsJARURI.cpp b/mozilla/netwerk/protocol/jar/src/nsJARURI.cpp
index f4aa388f0fa..877dad58381 100644
--- a/mozilla/netwerk/protocol/jar/src/nsJARURI.cpp
+++ b/mozilla/netwerk/protocol/jar/src/nsJARURI.cpp
@@ -335,12 +335,27 @@ nsJARURI::Resolve(const nsACString &relativePath, nsACString &result)
     }
 
     nsCAutoString path(mJAREntry);
-    PRInt32 pos = path.RFind("/");
-    if (pos >= 0)
-        path.Truncate(pos + 1);
-    else
-        path = "";
+    PRInt32 pos = 0;
 
+    char first = relativePath.Length() > 0 ? relativePath.First() : '#';
+
+    switch (first) {
+    case '/':
+        path = "";
+        break;
+    case '?':
+    case '#':
+        pos = path.RFindChar(first);
+        if (pos >= 0)
+            path.Truncate(pos);
+        break;
+    default:
+        pos = path.RFindChar('/');
+        if (pos >= 0)
+            path.Truncate(pos + 1);
+        else
+            path = "";
+    }
     nsCAutoString resolvedEntry;
     rv = net_ResolveRelativePath(relativePath, path,
                                  resolvedEntry);