diff --git a/src/input.cpp b/src/input.cpp
index e573b08f25..d843243c90 100644
--- a/src/input.cpp
+++ b/src/input.cpp
@@ -17,6 +17,7 @@
 #include "string.h"
 #include "input.h"
 #include "system.h"
+#include "universe.h"
 #include "atom.h"
 #include "comm.h"
 #include "group.h"
@@ -786,13 +787,17 @@ void Input::log()
     if (logfile) fclose(logfile);
     if (strcmp(arg[0],"none") == 0) logfile = NULL;
     else {
-      logfile = fopen(arg[0],"w");
+      char fname[128];
+      if (universe->nworlds == 1) strcpy(fname,arg[0]);
+      else sprintf(fname,"%s.%d",arg[0],universe->iworld);
+      logfile = fopen(fname,"w");
       if (logfile == NULL) {
 	char str[128];
-	sprintf(str,"Cannot open logfile %s",arg[0]);
+	sprintf(str,"Cannot open logfile %s",fname);
 	error->one(str);
       }
     }
+    if (universe->nworlds == 1) universe->ulogfile = logfile;
   }
 }
 
diff --git a/src/system.cpp b/src/system.cpp
index 1ee3afc87f..874a10ef00 100644
--- a/src/system.cpp
+++ b/src/system.cpp
@@ -174,7 +174,7 @@ void System::open(int narg, char **arg, MPI_Comm communicator)
       } else if (strcmp(arg[screenflag],"none") == 0)
 	screen = NULL;
       else {
-	char str[32];
+	char str[128];
 	sprintf(str,"%s.%d",arg[screenflag],universe->iworld);
 	screen = fopen(str,"w");
 	if (screen == NULL) error->one("Cannot open screen file");
@@ -190,7 +190,7 @@ void System::open(int narg, char **arg, MPI_Comm communicator)
       } else if (strcmp(arg[logflag],"none") == 0)
 	logfile = NULL;
       else {
-	char str[32];
+	char str[128];
 	sprintf(str,"%s.%d",arg[logflag],universe->iworld);
 	logfile = fopen(str,"w");
 	if (logfile == NULL) error->one("Cannot open logfile");
@@ -307,11 +307,13 @@ void System::destroy()
 
 void System::close()
 {
-  if (universe->nworlds > 1) {
+  if (universe->nworlds == 1) {
+    if (logfile) fclose(logfile);
+  } else {
     if (screen && screen != stdout) fclose(screen);
     if (logfile) fclose(logfile);
+    if (universe->ulogfile) fclose(universe->ulogfile);
   }
-  if (universe->ulogfile) fclose(universe->ulogfile);
 
   if (world != universe->uworld) MPI_Comm_free(&world);