diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index 7a0b2a8de8ce..8d0674f5e89d 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -2864,8 +2864,8 @@ nsresult nsPluginInstanceOwner::EnsureCachedAttrParamArrays()
   }
 
   // add our PARAM and null seperator
-  mCachedAttrParamNames [mNumCachedAttrs + 1] = "PARAM";
-  mCachedAttrParamValues[mNumCachedAttrs + 1] = nsnull;
+  mCachedAttrParamNames [mNumCachedAttrs] = ToNewUTF8String(NS_LITERAL_STRING("PARAM"));
+  mCachedAttrParamValues[mNumCachedAttrs] = nsnull;
 
   // now fill in the PARAM name/value pairs from the cached DOM nodes
   c = 0;
diff --git a/layout/html/base/src/nsObjectFrame.cpp b/layout/html/base/src/nsObjectFrame.cpp
index 7a0b2a8de8ce..8d0674f5e89d 100644
--- a/layout/html/base/src/nsObjectFrame.cpp
+++ b/layout/html/base/src/nsObjectFrame.cpp
@@ -2864,8 +2864,8 @@ nsresult nsPluginInstanceOwner::EnsureCachedAttrParamArrays()
   }
 
   // add our PARAM and null seperator
-  mCachedAttrParamNames [mNumCachedAttrs + 1] = "PARAM";
-  mCachedAttrParamValues[mNumCachedAttrs + 1] = nsnull;
+  mCachedAttrParamNames [mNumCachedAttrs] = ToNewUTF8String(NS_LITERAL_STRING("PARAM"));
+  mCachedAttrParamValues[mNumCachedAttrs] = nsnull;
 
   // now fill in the PARAM name/value pairs from the cached DOM nodes
   c = 0;
diff --git a/modules/plugin/base/src/ns4xPluginInstance.cpp b/modules/plugin/base/src/ns4xPluginInstance.cpp
index e217b7e57c1b..18df69995998 100644
--- a/modules/plugin/base/src/ns4xPluginInstance.cpp
+++ b/modules/plugin/base/src/ns4xPluginInstance.cpp
@@ -822,7 +822,7 @@ nsresult ns4xPluginInstance::InitializePlugin(nsIPluginInstancePeer* peer)
     const char* const* pnames = nsnull;
     const char* const* pvalues = nsnull;    
     if (NS_SUCCEEDED(taginfo->GetParameters(pcount, pnames, pvalues))) {
-      NS_ASSERTION(nsnull == values[count+1], "attribute/parameter array not setup correctly for 4.x plugins");
+      NS_ASSERTION(nsnull == values[count], "attribute/parameter array not setup correctly for 4.x plugins");
       count += ++pcount; //if it's all setup correctly, then all we need is to change the count
     }
   }