diff --git a/src/bias/MetaD.cpp b/src/bias/MetaD.cpp
index 28eb3feef160cd62ddc0353555093c7304162712..a0a13bcd34899a58da4d049677cd45039f1ee141 100644
--- a/src/bias/MetaD.cpp
+++ b/src/bias/MetaD.cpp
@@ -528,12 +528,12 @@ bool MetaD::readChunkOfGaussians(IFile *ifile, unsigned n)
   if(welltemp_){height*=(biasf_-1.0)/biasf_;}
   addGaussian(Gaussian(center,sigma,height,multivariate));
   if(nhills==n){
-      log.printf("      %d Gaussians read\n",nhills);
+      log.printf("      %u Gaussians read\n",nhills);
       return true;
   }
   nhills++;
  }     
- log.printf("      %d Gaussians read\n",nhills);
+ log.printf("      %u Gaussians read\n",nhills);
  return false;
 }
 
diff --git a/src/colvar/CS2Backbone.cpp b/src/colvar/CS2Backbone.cpp
index eb33d098b6c53e8a2cc2167fffb2ed0276bfa9ad..309b7a43afe227a881d7188bc2d6964ff191504d 100644
--- a/src/colvar/CS2Backbone.cpp
+++ b/src/colvar/CS2Backbone.cpp
@@ -314,7 +314,7 @@ PLUMED_COLVAR_INIT(ao)
   unsigned stride=comm.Get_size();
   unsigned rank=comm.Get_rank();
   if(serial) {stride=1; rank=0;}
-  if(stride>1) log.printf("  Parallelized over %d processors\n", stride);
+  if(stride>1) log.printf("  Parallelized over %u processors\n", stride);
   a.set_mpi(stride, rank);
   
   if(ensemble) { log.printf("  ENSEMBLE averaging over %i replicas\n", ens_dim); }
diff --git a/src/colvar/PathMSDBase.cpp b/src/colvar/PathMSDBase.cpp
index 16c166dc75a207ce40895cc20622960ff35846f7..e741bc58280e98f25bff9f212527ea6c3d5ccda6 100644
--- a/src/colvar/PathMSDBase.cpp
+++ b/src/colvar/PathMSDBase.cpp
@@ -93,7 +93,7 @@ nframes(0)
            }
            log.printf("  Neighbor list enabled: \n");
            log.printf("                size   :  %d elements\n",neigh_size);
-           log.printf("                stride :  %f timesteps \n",neigh_stride);
+           log.printf("                stride :  %d timesteps \n",neigh_stride);
   }else{
            log.printf("  Neighbor list NOT enabled \n");
   }
diff --git a/src/main/main.cpp b/src/main/main.cpp
index b291e0a693318c40bcded75da424fdaa27cacc37..f75f6535e44c5468c20db540389670d4e7ccfc0a 100644
--- a/src/main/main.cpp
+++ b/src/main/main.cpp
@@ -41,7 +41,7 @@ int main(int argc,char**argv){
   if(argc>1 && !strcmp(argv[1],"--no-mpi")) nompi=true;
   if(!nompi) MPI_Init(&argc,&argv);
 #endif
-  int ret;
+  int ret=0;
 
   PLMD::Plumed* p=new PLMD::Plumed;
   p->cmd("CLTool setArgc",&argc);