diff --git a/CondFormats/L1TObjects/src/L1MuDTEtaPatternLut.cc b/CondFormats/L1TObjects/src/L1MuDTEtaPatternLut.cc
index 8c2334765028c..0dbaa540a0411 100644
--- a/CondFormats/L1TObjects/src/L1MuDTEtaPatternLut.cc
+++ b/CondFormats/L1TObjects/src/L1MuDTEtaPatternLut.cc
@@ -78,7 +78,7 @@ int L1MuDTEtaPatternLut::load() {
 
   // assemble file name
   edm::FileInPath lut_f = edm::FileInPath(string(defaultPath + eau_dir + "ETFPatternList.lut"));
-  string etf_file = lut_f.fullPath();
+  const string& etf_file = lut_f.fullPath();
 
   // open file
   L1TriggerLutFile file(etf_file);
diff --git a/CondFormats/L1TObjects/src/L1MuDTExtLut.cc b/CondFormats/L1TObjects/src/L1MuDTExtLut.cc
index c1780afab1317..d04d63c9646bc 100644
--- a/CondFormats/L1TObjects/src/L1MuDTExtLut.cc
+++ b/CondFormats/L1TObjects/src/L1MuDTExtLut.cc
@@ -141,7 +141,7 @@ int L1MuDTExtLut::load() {
 
     // assemble file name
     edm::FileInPath lut_f = edm::FileInPath(string(defaultPath + ext_dir + ext_str + ".lut"));
-    string ext_file = lut_f.fullPath();
+    const string& ext_file = lut_f.fullPath();
 
     // open file
     L1TriggerLutFile file(ext_file);
diff --git a/CondFormats/L1TObjects/src/L1MuDTPhiLut.cc b/CondFormats/L1TObjects/src/L1MuDTPhiLut.cc
index 4f61b1c5e2cc1..aa9c952ad49d3 100644
--- a/CondFormats/L1TObjects/src/L1MuDTPhiLut.cc
+++ b/CondFormats/L1TObjects/src/L1MuDTPhiLut.cc
@@ -110,7 +110,7 @@ int L1MuDTPhiLut::load() {
 
     // assemble file name
     edm::FileInPath lut_f = edm::FileInPath(string(defaultPath + phi_dir + phi_str + ".lut"));
-    string phi_file = lut_f.fullPath();
+    const string& phi_file = lut_f.fullPath();
 
     // open file
     L1TriggerLutFile file(phi_file);
diff --git a/CondFormats/L1TObjects/src/L1MuDTPtaLut.cc b/CondFormats/L1TObjects/src/L1MuDTPtaLut.cc
index 0219c5e979523..6d9c002022e50 100644
--- a/CondFormats/L1TObjects/src/L1MuDTPtaLut.cc
+++ b/CondFormats/L1TObjects/src/L1MuDTPtaLut.cc
@@ -221,7 +221,7 @@ int L1MuDTPtaLut::load() {
 
     // assemble file name
     edm::FileInPath lut_f = edm::FileInPath(string(defaultPath + pta_dir + pta_str + ".lut"));
-    string pta_file = lut_f.fullPath();
+    const string& pta_file = lut_f.fullPath();
 
     // open file
     L1TriggerLutFile file(pta_file);
diff --git a/CondFormats/L1TObjects/src/L1MuDTQualPatternLut.cc b/CondFormats/L1TObjects/src/L1MuDTQualPatternLut.cc
index 8f5d2d43b578f..7dd1de0246e7a 100644
--- a/CondFormats/L1TObjects/src/L1MuDTQualPatternLut.cc
+++ b/CondFormats/L1TObjects/src/L1MuDTQualPatternLut.cc
@@ -118,7 +118,7 @@ int L1MuDTQualPatternLut::load() {
 
     // assemble file name
     edm::FileInPath lut_f = edm::FileInPath(string(defaultPath + eau_dir + emu_str + ".lut"));
-    string emu_file = lut_f.fullPath();
+    const string& emu_file = lut_f.fullPath();
 
     // open file
     L1TriggerLutFile file(emu_file);