diff --git a/src/analysis/Analysis.cpp b/src/analysis/Analysis.cpp
index c108897c0066de11ffc7e9b0ec5ef48cdcc4ba74..d427897d4aef73f703089695b5017c6d6a6aa26a 100644
--- a/src/analysis/Analysis.cpp
+++ b/src/analysis/Analysis.cpp
@@ -326,7 +326,7 @@ void Analysis::runFinalJobs() {
   runAnalysis(); 
 }
 
-std::string Analysis::saveResultsFromPreviousAnalyses( const std::string filename ){
+std::string Analysis::saveResultsFromPreviousAnalyses( const std::string & filename ){
   FILE* ff=std::fopen( filename.c_str() ,"r");
   // Perhaps replace this with an warning and a backup at some stage
   if(ff && !firstAnalysisDone) error("found file named " + filename + " from previous calculation");
diff --git a/src/analysis/Analysis.h b/src/analysis/Analysis.h
index 9d3711dc823ad30e9c13f1fdf99df34b0fdb392e..092e1890520fa40e5daa2e85c27077a89f801718 100644
--- a/src/analysis/Analysis.h
+++ b/src/analysis/Analysis.h
@@ -101,7 +101,7 @@ protected:
 /// Are we analyzing each data block separately (if we are not this also returns the old normalization )
   bool usingMemory() const; 
 /// Save the results in files from previous runs of the analysis algorithm
-  std::string saveResultsFromPreviousAnalyses( const std::string filename );
+  std::string saveResultsFromPreviousAnalyses( const std::string & filename );
 /// Convert the stored log weights to proper weights
   void finalizeWeights( const bool& ignore_weights );
 /// Overwrite ActionWithArguments getArguments() so that we don't return
diff --git a/src/colvar/PropertyMap.cpp b/src/colvar/PropertyMap.cpp
index a096a24c62cc5122f68203b69e45d4b83f613314..888900d8628f41313f3fd6cc4494c7340f4d7c9a 100644
--- a/src/colvar/PropertyMap.cpp
+++ b/src/colvar/PropertyMap.cpp
@@ -101,7 +101,7 @@ PathMSDBase(ao)
   }else{
       for(unsigned i=0;i<labels.size();i++){
 	log<<" found custom propety to be found in the REMARK line: "<<labels[i].c_str()<<"\n";
-        addComponentWithDerivatives(labels[i].c_str()); componentIsNotPeriodic(labels[i].c_str());
+        addComponentWithDerivatives(labels[i]); componentIsNotPeriodic(labels[i]);
       }
       // add distance anyhow
       addComponentWithDerivatives("zzz"); componentIsNotPeriodic("zzz");
diff --git a/src/tools/Keywords.cpp b/src/tools/Keywords.cpp
index 186b219a568c627ee281bc2d698b7b7aa2452af6..eb7373948697ab6cdd8ccc3cd0b9426e6d7849d4 100644
--- a/src/tools/Keywords.cpp
+++ b/src/tools/Keywords.cpp
@@ -125,7 +125,7 @@ void Keywords::reserveFlag( const std::string & k, const bool def, const std::st
   reserved_keys.push_back(k); 
 }
 
-void Keywords::use( const std::string k ){
+void Keywords::use( const std::string & k ){
   plumed_massert( reserved(k), "the " + k + " keyword is not reserved");
   for(unsigned i=0;i<reserved_keys.size();++i){
      if(reserved_keys[i]==k) keys.push_back( reserved_keys[i] ); 
diff --git a/src/tools/Keywords.h b/src/tools/Keywords.h
index 345d278ba0628a273972d1c34a37f55aa6e1abf1..ebbb77665e6ad6c3cd62057b263d8532947e754e 100644
--- a/src/tools/Keywords.h
+++ b/src/tools/Keywords.h
@@ -98,7 +98,7 @@ public:
 /// Reserve a flag
   void reserveFlag( const std::string & k, const bool def, const std::string & d );
 /// Use one of the reserved keywords
-  void use( const std::string  k );
+  void use( const std::string  & k );
 /// Get the ith keyword
   std::string get( const unsigned k ) const ;
 /// Add a new keyword of type t with name k and description d
diff --git a/src/tools/Tensor.h b/src/tools/Tensor.h
index ff9d82cdd9a55b704e80b45bf7bff980b840fa59..f2ca4f61493ee6e428240c3f5da98a977ad3c50b 100644
--- a/src/tools/Tensor.h
+++ b/src/tools/Tensor.h
@@ -146,7 +146,7 @@ public:
   friend VectorGeneric<n_> matmul(const TensorGeneric<n_,m_>&,const TensorGeneric<m_,l_>&,const VectorGeneric<l_>&);
 /// vector-matrix-matrix multiplication
   template<unsigned n_,unsigned m_,unsigned l_>
-  friend VectorGeneric<l_> matmul(const VectorGeneric<n_>,const TensorGeneric<n_,m_>&,const TensorGeneric<m_,l_>&);
+  friend VectorGeneric<l_> matmul(const VectorGeneric<n_>&,const TensorGeneric<n_,m_>&,const TensorGeneric<m_,l_>&);
 /// returns the determinant of a tensor
   friend double determinant(const TensorGeneric<3,3>&);
 /// returns the inverse of a tensor (same as inverse())
@@ -373,7 +373,7 @@ VectorGeneric<n> matmul(const TensorGeneric<n,m>&a,const TensorGeneric<m,l>&b,co
 }
 
 template<unsigned n,unsigned m,unsigned l> 
-VectorGeneric<l> matmul(const VectorGeneric<n>a,const TensorGeneric<n,m>&b,const TensorGeneric<m,l>&c){
+VectorGeneric<l> matmul(const VectorGeneric<n>&a,const TensorGeneric<n,m>&b,const TensorGeneric<m,l>&c){
   return matmul(matmul(a,b),c);
 }
 
diff --git a/src/wrapper/Plumed.h b/src/wrapper/Plumed.h
index 77f93716df521a306e858db6b34660ca542fa2b3..c992d75cf3dc753c79c0a1d3ef7795d7a64bf602 100644
--- a/src/wrapper/Plumed.h
+++ b/src/wrapper/Plumed.h
@@ -426,22 +426,21 @@ bool Plumed::installed(){
 
 inline
 Plumed::Plumed():
-  cloned(false){
-  main=plumed_create();
-}
+  main(plumed_create()),
+  cloned(false)
+{}
 
 inline
 Plumed::Plumed(const char*c):
-  cloned(true){
-  main=plumed_f2c(c);
-}
+  main(plumed_f2c(c)),
+  cloned(true)
+{}
 
 inline
 Plumed::Plumed(plumed p):
+  main(p),
   cloned(true)
-{
-  main=p;
-}
+{}
 
 inline
 Plumed::operator plumed()const{