diff --git a/MC/config/PWGEM/external/generator/Generator_pythia8_GapTriggered_LFmumu.C b/MC/config/PWGEM/external/generator/Generator_pythia8_GapTriggered_LFmumu.C
index a2417eae3..3f2e4c68b 100644
--- a/MC/config/PWGEM/external/generator/Generator_pythia8_GapTriggered_LFmumu.C
+++ b/MC/config/PWGEM/external/generator/Generator_pythia8_GapTriggered_LFmumu.C
@@ -63,6 +63,7 @@ class GeneratorPythia8GapTriggeredLFmumu : public GeneratorPythia8 {
       useLMeeDecaytable=useLMeeDecaytable.ReplaceAll("${O2DPG_ROOT}",O2DPG_ROOT);
       decayer->SetDecayTableFile(useLMeeDecaytable.Data());
       decayer->ReadDecayTable();
+      decayer->DecayToDimuons();
 
       //Param
       GeneratorParamEMlib *emlib = new GeneratorParamEMlib();
diff --git a/MC/config/PWGEM/ini/Generator_GapTriggered_LFmumu.ini b/MC/config/PWGEM/ini/Generator_GapTriggered_LFmumu.ini
index 08861875b..f49c0b6d0 100644
--- a/MC/config/PWGEM/ini/Generator_GapTriggered_LFmumu.ini
+++ b/MC/config/PWGEM/ini/Generator_GapTriggered_LFmumu.ini
@@ -3,7 +3,7 @@
 
 [GeneratorExternal]
 fileName = ${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGEM/external/generator/Generator_pythia8_GapTriggered_LFmumu.C
-funcName = GeneratorPythia8GapTriggeredLFmumu_ForEM(5+1, -4.3, -2.2, 1, 1)
+funcName = GeneratorPythia8GapTriggeredLFmumu_ForEM(4+1, -4.3, -2.2, 1, 1)
 
 [GeneratorPythia8]
 config = ${O2DPG_MC_CONFIG_ROOT}/MC/config/PWGEM/pythia8/generator/pythia8_MB_gapevent.cfg