diff -r 2fd64ea0a7cb -r 52df7c56508b src/arch/x86/tlb.cc
--- a/src/arch/x86/tlb.cc	Tue Mar 08 17:51:02 2016 -0500
+++ b/src/arch/x86/tlb.cc	Fri Mar 25 15:42:42 2016 +0000
@@ -101,10 +101,23 @@
 {
     // If somebody beat us to it, just use that existing entry.
     TlbEntry *newEntry = trie.lookup(vpn);
-    if (newEntry) {
+    if (newEntry && newEntry->logBytes == entry.logBytes) {
         assert(newEntry->vaddr == vpn);
         return newEntry;
     }
+    // We have at least one matching entry with a different mask,
+    // remove it before inserting the new one.
+    if (newEntry && newEntry->trieHandle) {
+        for (unsigned i = 0; i < size; i++) {
+            if (tlb[i].trieHandle &&
+                tlb[i].trieHandle == newEntry->trieHandle) {
+
+                trie.remove(tlb[i].trieHandle);
+                tlb[i].trieHandle = NULL;
+                freeList.push_back(&tlb[i]);
+            }
+        }
+    }
 
     if (freeList.empty())
         evictLRU();