diff --git a/src/collection/backend/lmdb.cc b/src/collection/backend/lmdb.cc
index 1ffca80a..fd22b54e 100644
--- a/src/collection/backend/lmdb.cc
+++ b/src/collection/backend/lmdb.cc
@@ -37,7 +37,7 @@ namespace backend {
 
 #ifdef WITH_LMDB
 
-LMDB::LMDB(std::string name) :
+LMDB::LMDB(const std::string &name) :
     Collection(name), m_env(NULL), isOpen(false) {}
 
 int LMDB::txn_begin(unsigned int flags, MDB_txn **ret) {
@@ -60,7 +60,7 @@ void LMDB::string2val(const std::string& str, MDB_val *val) {
 }
 
 
-void LMDB::lmdb_debug(int rc, std::string op, std::string scope) {
+void LMDB::lmdb_debug(int rc, const std::string &op, const std::string &scope) {
 #ifndef LMDB_STDOUT_COUT
     return;
 #else
diff --git a/src/collection/backend/lmdb.h b/src/collection/backend/lmdb.h
index 3baa9145..37177c52 100644
--- a/src/collection/backend/lmdb.h
+++ b/src/collection/backend/lmdb.h
@@ -97,7 +97,7 @@ class MDBEnvProvider {
 class LMDB :
     public Collection {
  public:
-    explicit LMDB(std::string name);
+    explicit LMDB(const std::string &name);
     void store(std::string key, std::string value) override;
 
     bool storeOrUpdateFirst(const std::string &key,
@@ -122,7 +122,7 @@ class LMDB :
  private:
     int txn_begin(unsigned int flags, MDB_txn **ret);
     void string2val(const std::string& str, MDB_val *val);
-    void inline lmdb_debug(int rc, std::string op, std::string scope);
+    void inline lmdb_debug(int rc, const std::string &op, const std::string &scope);
 
     MDB_env *m_env;
     MDB_dbi m_dbi;
diff --git a/test/cppcheck_suppressions.txt b/test/cppcheck_suppressions.txt
index 764a2dae..821a3d10 100644
--- a/test/cppcheck_suppressions.txt
+++ b/test/cppcheck_suppressions.txt
@@ -68,7 +68,6 @@ uninitvar:src/operators/verify_svnr.cc:67
 functionConst:src/collection/backend/lmdb.h:86
 unusedLabel:src/collection/backend/lmdb.cc:297
 
-passedByValue:src/collection/backend/lmdb.cc
 variableScope:src/operators/rx.cc
 variableScope:src/operators/rx_global.cc