diff --git a/DQMOffline/L1Trigger/python/L1TPhase2MuonDQMEfficiency_cfi.py b/DQMOffline/L1Trigger/python/L1TPhase2MuonDQMEfficiency_cfi.py
index 761ed7247c863..c5f61fe2b5c4f 100644
--- a/DQMOffline/L1Trigger/python/L1TPhase2MuonDQMEfficiency_cfi.py
+++ b/DQMOffline/L1Trigger/python/L1TPhase2MuonDQMEfficiency_cfi.py
@@ -5,7 +5,7 @@ def generateEfficiencyStrings(ptQualCuts):
     numDenDir = "nums_and_dens/"
     varStrings = ['Pt', 'Eta', 'Phi']
     etaStrings = ['etaMin0_etaMax0p83', 'etaMin0p83_etaMax1p24', 'etaMin1p24_etaMax2p4', 'etaMin0_etaMax2p4']
-    qualStrings = {'qualOpen', 'qualDouble', 'qualSingle'}
+    qualStrings = ['qualOpen', 'qualDouble', 'qualSingle']
     muonStrings = ['SAMuon','TkMuon'] 
 
     efficiencyStrings = []