diff --git a/checkin_notes b/checkin_notes
index e1ed7467ff..64c6c16ec5 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -4404,3 +4404,11 @@ David  18 Jun 2010
         sched_types.cpp
     client/
         check_state.cpp
+
+David  18 Jun 2010
+    - validator: because of the above problem,
+        some results have flops_estimate == 0, which causes divide by zero.
+        Check for this and use 1e10.
+
+    sched/
+        credit.cpp
diff --git a/sched/credit.cpp b/sched/credit.cpp
index b988a4064e..66b6ef7532 100644
--- a/sched/credit.cpp
+++ b/sched/credit.cpp
@@ -443,6 +443,14 @@ int get_pfc(
         return 0;
     }
 
+    // r.flops_estimate shouldn't be zero,
+    // but (because of scheduler bug) it can be.
+    // At this point we don't have much to go on, so use 1e10.
+    //
+    if (!r.flops_estimate) {
+        r.flops_estimate = 1e10;
+    }
+
     double raw_pfc = (r.elapsed_time * r.flops_estimate);
     if (config.debug_credit) {
         log_messages.printf(MSG_NORMAL,