diff --git a/checkin_notes b/checkin_notes
index 666b171a1f..47f3b56d77 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -5731,3 +5731,11 @@ David  8 Sept 2011
 
     html/inc/
         result.inc
+
+David  8 Sept 2011
+    - validator: old scheduler bugs may cause result.flops_estimate
+        to be negative in some cases.
+        Detect this, and use 1e10 instead
+
+    sched/
+        credit.cpp
diff --git a/sched/credit.cpp b/sched/credit.cpp
index b59d256c61..24756a8c0e 100644
--- a/sched/credit.cpp
+++ b/sched/credit.cpp
@@ -467,11 +467,11 @@ int get_pfc(
         return 0;
     }
 
-    // r.flops_estimate shouldn't be zero,
-    // but (because of scheduler bug) it can be.
+    // r.flops_estimate should be positive
+    // but (because of scheduler bug) it may not be.
     // At this point we don't have much to go on, so use 1e10.
     //
-    if (!r.flops_estimate) {
+    if (r.flops_estimate <= 0) {
         r.flops_estimate = 1e10;
     }