diff --git a/Generators/EvgenJobTransforms/share/skel.ABtoEVGEN.py b/Generators/EvgenJobTransforms/share/skel.ABtoEVGEN.py
index 3a5ea571681cc5c6fe85668eca3b2376f9796414..e87359112229fa7fd6f0dc9e866ebbc7b8af93ee 100644
--- a/Generators/EvgenJobTransforms/share/skel.ABtoEVGEN.py
+++ b/Generators/EvgenJobTransforms/share/skel.ABtoEVGEN.py
@@ -325,6 +325,12 @@ else:
     postSeq.CountHepMC.RequestedOutput = evgenConfig.nEventsPerJob if runArgs.maxEvents == -1  else runArgs.maxEvents
     evgenLog.info('Requested output events = '+str(postSeq.CountHepMC.RequestedOutput))
 
+    # Special case of N<100: adjust TestHepMC. We will allow _one_ event to fail the checks.
+    # This means the minimum efficiency is N/N+1 for N generated events. Note that if N<100,
+    # each failed event costs us more than 1% of efficiency.
+    if hasattr(testSeq, "TestHepMC") and postSeq.CountHepMC.RequestedOutput<100:
+        testSeq.TestHepMC.EffFailThreshold = postSeq.CountHepMC.RequestedOutput/(postSeq.CountHepMC.RequestedOutput+1) - 0.01
+
 ## Check that the keywords are in the list of allowed words (and exit if processing an official JO)
 if evgenConfig.keywords:
     from GeneratorConfig.GenConfigHelpers import checkKeywords
diff --git a/Generators/EvgenJobTransforms/share/skel.GENtoEVGEN.py b/Generators/EvgenJobTransforms/share/skel.GENtoEVGEN.py
index f58a9f231a771b90a096938e16a66a29493ca683..a3f8687cf1103b7df7434f267d6b33dd41f3c84c 100644
--- a/Generators/EvgenJobTransforms/share/skel.GENtoEVGEN.py
+++ b/Generators/EvgenJobTransforms/share/skel.GENtoEVGEN.py
@@ -372,6 +372,12 @@ else:
     postSeq.CountHepMC.RequestedOutput = evgenConfig.nEventsPerJob if runArgs.maxEvents == -1  else runArgs.maxEvents
     evgenLog.info('Requested output events = '+str(postSeq.CountHepMC.RequestedOutput))
 
+    # Special case of N<100: adjust TestHepMC. We will allow _one_ event to fail the checks.
+    # This means the minimum efficiency is N/N+1 for N generated events. Note that if N<100,
+    # each failed event costs us more than 1% of efficiency.
+    if hasattr(testSeq, "TestHepMC") and postSeq.CountHepMC.RequestedOutput<100:
+        testSeq.TestHepMC.EffFailThreshold = postSeq.CountHepMC.RequestedOutput/(postSeq.CountHepMC.RequestedOutput+1) - 0.01
+
 ## Check that the keywords are in the list of allowed words (and exit if processing an official JO)
 if evgenConfig.keywords:
     from GeneratorConfig.GenConfigHelpers import checkKeywords