diff --git a/src/fix_ave_spatial.cpp b/src/fix_ave_spatial.cpp
index bcdac37402..bf48b26030 100644
--- a/src/fix_ave_spatial.cpp
+++ b/src/fix_ave_spatial.cpp
@@ -242,9 +242,9 @@ FixAveSpatial::FixAveSpatial(LAMMPS *lmp, int narg, char **arg) :
   // print header into file
 
   if (fp && me == 0) {
-    fprintf(fp,"Spatial-averaged data for fix %s and group %s\n",id,arg[1]);
-    fprintf(fp,"TimeStep Number-of-layers\n");
-    fprintf(fp,"Layer Coordinate Natoms");
+    fprintf(fp,"# Spatial-averaged data for fix %s and group %s\n",id,arg[1]);
+    fprintf(fp,"# TimeStep Number-of-layers\n");
+    fprintf(fp,"# Layer Coordinate Natoms");
     for (int i = 0; i < nvalues; i++)
       if (which[i] == COMPUTE) fprintf(fp," c_%s",ids[i]);
       else if (which[i] == FIX) fprintf(fp," f_%s",ids[i]);
diff --git a/src/fix_ave_time.cpp b/src/fix_ave_time.cpp
index 366600f691..c8ff49945a 100644
--- a/src/fix_ave_time.cpp
+++ b/src/fix_ave_time.cpp
@@ -167,8 +167,8 @@ FixAveTime::FixAveTime(LAMMPS *lmp, int narg, char **arg) :
   // print header into file
 
   if (fp && me == 0) {
-    fprintf(fp,"Time-averaged data for fix %s\n",id);
-    fprintf(fp,"TimeStep");
+    fprintf(fp,"# Time-averaged data for fix %s\n",id);
+    fprintf(fp,"# TimeStep");
     for (int i = 0; i < nvalues; i++)
       if (which[i] == COMPUTE) fprintf(fp," c_%s",ids[i]);
       else if (which[i] == FIX) fprintf(fp," f_%s",ids[i]);
diff --git a/src/fix_com.cpp b/src/fix_com.cpp
index 689d48505b..37b05ee0cf 100644
--- a/src/fix_com.cpp
+++ b/src/fix_com.cpp
@@ -42,8 +42,8 @@ FixCOM::FixCOM(LAMMPS *lmp, int narg, char **arg) :
   }
 
   if (me == 0) {
-    fprintf(fp,"Center-of-mass for group %s\n",group->names[igroup]);
-    fprintf(fp,"TimeStep x y z\n");
+    fprintf(fp,"# Center-of-mass for group %s\n",group->names[igroup]);
+    fprintf(fp,"# TimeStep x y z\n");
   }
 }
 
diff --git a/src/fix_tmd.cpp b/src/fix_tmd.cpp
index 14e612e020..39d623aed7 100644
--- a/src/fix_tmd.cpp
+++ b/src/fix_tmd.cpp
@@ -78,7 +78,7 @@ FixTMD::FixTMD(LAMMPS *lmp, int narg, char **arg) :
 	sprintf(str,"Cannot open fix tmd file %s",arg[6]);
 	error->one(str);
       }
-      fprintf(fp,"%s %s\n","Step rho_target rho_old gamma_back",
+      fprintf(fp,"%s %s\n","# Step rho_target rho_old gamma_back",
 	      "gamma_forward lambda work_lambda work_analytical");
     }
   }