diff -r 1c2fe07bc7b7 -r f74b7b7af31d src/cpu/o3/fu_pool.hh
--- a/src/cpu/o3/fu_pool.hh	Wed Jun 05 08:44:38 2013 +0100
+++ b/src/cpu/o3/fu_pool.hh	Wed Jun 05 09:55:23 2013 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012 ARM Limited
+ * Copyright (c) 2012-2013 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -169,8 +169,8 @@
         return maxIssueLatencies[capability];
     }
 
-    /** Perform sanity checks after a drain. */
-    void drainSanityCheck() const;
+    /** Have all the FUs drained? */
+    bool isDrained() const;
 
     /** Takes over from another CPU's thread. */
     void takeOverFrom() {};
diff -r 1c2fe07bc7b7 -r f74b7b7af31d src/cpu/o3/fu_pool.cc
--- a/src/cpu/o3/fu_pool.cc	Wed Jun 05 08:44:38 2013 +0100
+++ b/src/cpu/o3/fu_pool.cc	Wed Jun 05 09:55:23 2013 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012 ARM Limited
+ * Copyright (c) 2012-2013 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -255,12 +255,14 @@
     }
 }
 
-void
-FUPool::drainSanityCheck() const
+bool
+FUPool::isDrained() const
 {
-    assert(unitsToBeFreed.empty());
+    bool is_drained = true;
     for (int i = 0; i < numFU; i++)
-        assert(!unitBusy[i]);
+        is_drained = is_drained && !unitBusy[i];
+
+    return is_drained;
 }
 
 //
diff -r 1c2fe07bc7b7 -r f74b7b7af31d src/cpu/o3/iew_impl.hh
--- a/src/cpu/o3/iew_impl.hh	Wed Jun 05 08:44:38 2013 +0100
+++ b/src/cpu/o3/iew_impl.hh	Wed Jun 05 09:55:23 2013 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010-2012 ARM Limited
+ * Copyright (c) 2010-2013 ARM Limited
  * All rights reserved.
  *
  * The license below extends only to copyright in the software and shall
@@ -376,6 +376,14 @@
         }
     }
 
+    // Also check the FU pool as instructions are "stored" in FU
+    // completion events until they are done and not accounted for
+    // above
+    if (drained && !fuPool->isDrained()) {
+        DPRINTF(Drain, "FU pool still busy.\n");
+        drained = false;
+    }
+
     return drained;
 }
 
@@ -387,7 +395,6 @@
 
     instQueue.drainSanityCheck();
     ldstQueue.drainSanityCheck();
-    fuPool->drainSanityCheck();
 }
 
 template <class Impl>