diff --git a/addrcheck/ac_main.c b/addrcheck/ac_main.c
index f202276..73e0de4 100644
--- a/addrcheck/ac_main.c
+++ b/addrcheck/ac_main.c
@@ -1030,6 +1030,9 @@
              }
              break;
 
+         case Ist_MFence:
+            break;
+
          default:
             VG_(printf)("\n");
             ppIRStmt(st);
@@ -1089,7 +1092,7 @@
       }
 
       /* And finally, copy the expr itself to the output. */
-      addStmtToIRBB( bb, dopyIRStmt(st));
+      addStmtToIRBB( bb, st );
    }
 
    return bb;