diff --git a/extensions/spellcheck/src/mozEnglishWordUtils.cpp b/extensions/spellcheck/src/mozEnglishWordUtils.cpp
index e402a18c5fcf..fecada5dbaba 100644
--- a/extensions/spellcheck/src/mozEnglishWordUtils.cpp
+++ b/extensions/spellcheck/src/mozEnglishWordUtils.cpp
@@ -273,6 +273,10 @@ NS_IMETHODIMP mozEnglishWordUtils::FromRootForm(const PRUnichar *aWord, const PR
   for(PRUint32 i = 0; i < icount; ++i) {
     length = nsCRT::strlen(iwords[i]);
     tmpPtr[i] = (PRUnichar *) nsMemory::Alloc(sizeof(PRUnichar) * (length + 1));
+    if (NS_UNLIKELY(!tmpPtr[i])) {
+      NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(i, tmpPtr);
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
     memcpy(tmpPtr[i], iwords[i], (length + 1) * sizeof(PRUnichar));
 
     nsAutoString capTest(tmpPtr[i]);