diff --git a/rdf/base/nsRDFService.cpp b/rdf/base/nsRDFService.cpp
index 368b2d30ac645..13a5e719586a3 100644
--- a/rdf/base/nsRDFService.cpp
+++ b/rdf/base/nsRDFService.cpp
@@ -1298,8 +1298,10 @@ RDFServiceImpl::GetDataSource(const char* aURI, bool aBlock, nsIRDFDataSource**
     if (!StringBeginsWith(spec, NS_LITERAL_CSTRING("rdf:"))) {
         nsCOMPtr<nsIURI> uri;
         NS_NewURI(getter_AddRefs(uri), spec);
-        if (uri)
-            uri->GetSpec(spec);
+        if (uri) {
+            rv = uri->GetSpec(spec);
+            if (NS_FAILED(rv)) return rv;
+        }
     }
 
     // First, check the cache to see if we already have this
diff --git a/rdf/base/nsRDFXMLDataSource.cpp b/rdf/base/nsRDFXMLDataSource.cpp
index e108a7b0ba116..62d6c93dd3e2c 100644
--- a/rdf/base/nsRDFXMLDataSource.cpp
+++ b/rdf/base/nsRDFXMLDataSource.cpp
@@ -604,14 +604,15 @@ RDFXMLDataSourceImpl::GetURI(char* *aURI)
     if (!mURL) {
         return NS_OK;
     }
-    
+
     nsAutoCString spec;
-    mURL->GetSpec(spec);
+    nsresult rv = mURL->GetSpec(spec);
+    NS_ENSURE_SUCCESS(rv, rv);
     *aURI = ToNewCString(spec);
     if (!*aURI) {
         return NS_ERROR_OUT_OF_MEMORY;
     }
-    
+
     return NS_OK;
 }
 
diff --git a/startupcache/test/TestStartupCache.cpp b/startupcache/test/TestStartupCache.cpp
index 3236f79a3a9f7..a16c2de727322 100644
--- a/startupcache/test/TestStartupCache.cpp
+++ b/startupcache/test/TestStartupCache.cpp
@@ -155,7 +155,8 @@ TestWriteObject() {
     return NS_ERROR_UNEXPECTED;
   }
   NS_NAMED_LITERAL_CSTRING(spec, "http://www.mozilla.org");
-  obj->SetSpec(spec);
+  rv = obj->SetSpec(spec);
+  NS_ENSURE_SUCCESS(rv, rv);
   nsCOMPtr<nsIStartupCache> sc = do_GetService("@mozilla.org/startupcache/cache;1", &rv);
 
   sc->InvalidateCache();
@@ -232,7 +233,11 @@ TestWriteObject() {
   nsCOMPtr<nsIURI> uri(do_QueryInterface(deserialized));
   if (uri) {
     nsCString outSpec;
-    uri->GetSpec(outSpec);
+    rv = uri->GetSpec(outSpec);
+    if (NS_FAILED(rv)) {
+      fail("failed to get spec");
+      return rv;
+    }
     match = outSpec.Equals(spec);
   }
   if (!match) {
diff --git a/xpfe/components/directory/nsDirectoryViewer.cpp b/xpfe/components/directory/nsDirectoryViewer.cpp
index 08a158394193d..88ab134797a49 100644
--- a/xpfe/components/directory/nsDirectoryViewer.cpp
+++ b/xpfe/components/directory/nsDirectoryViewer.cpp
@@ -273,13 +273,14 @@ nsHTTPIndex::OnStartRequest(nsIRequest *request, nsISupports* aContext)
     // now create the top most resource
     nsCOMPtr<nsIURI> uri;
     channel->GetURI(getter_AddRefs(uri));
-      
+
     nsAutoCString entryuriC;
-    uri->GetSpec(entryuriC);
+    rv = uri->GetSpec(entryuriC);
+    if (NS_FAILED(rv)) return rv;
 
     nsCOMPtr<nsIRDFResource> entry;
     rv = mDirRDF->GetResource(entryuriC, getter_AddRefs(entry));
-    
+
     NS_ConvertUTF8toUTF16 uriUnicode(entryuriC);
 
     nsCOMPtr<nsIRDFLiteral> URLVal;