diff --git a/src/Makefile b/src/Makefile
index 2ae1181eee..4211025cf7 100755
--- a/src/Makefile
+++ b/src/Makefile
@@ -147,21 +147,21 @@ package:
 	@echo ''
 	@echo 'User-contributed packages:' $(PACKUSER)
 	@echo ''
-	@echo 'make package             list available packages'
-	@echo 'make package-status (ps) status of all packages'
-	@echo 'make yes-package         install a single package in src dir'
-	@echo 'make no-package          remove a single package from src dir'
-	@echo 'make yes-all             install all packages in src dir'
-	@echo 'make no-all              remove all packages from src dir'
-	@echo 'make yes-standard        install all standard packages'
-	@echo 'make no-standard         remove all standard packages'
-	@echo 'make yes-user            install all user packages'
-	@echo 'make no-user             remove all user packages'
-	@echo 'make no-lib              remove all packages with external libs'
+	@echo 'make package              list available packages'
+	@echo 'make package-status (ps)  status of all packages'
+	@echo 'make yes-package          install a single package in src dir'
+	@echo 'make no-package           remove a single package from src dir'
+	@echo 'make yes-all              install all packages in src dir'
+	@echo 'make no-all               remove all packages from src dir'
+	@echo 'make yes-standard         install all standard packages'
+	@echo 'make no-standard          remove all standard packages'
+	@echo 'make yes-user             install all user packages'
+	@echo 'make no-user              remove all user packages'
+	@echo 'make no-lib               remove all packages with external libs'
 	@echo ''
-	@echo 'make package-update (pu)    replace src files with package files'
-	@echo 'make package-overwrite (po) replace package files with src files'
-	@echo 'make package-diff           diff src files against package file'
+	@echo 'make package-update (pu)  replace src files with package files'
+	@echo 'make package-overwrite    replace package files with src files'
+	@echo 'make package-diff (pd)    diff src files against package file'
 
 yes-all:
 	@for p in $(PACKALL); do $(MAKE) yes-$$p; done
@@ -229,12 +229,12 @@ package-update pu:
 	@echo ''
 	@for p in $(PACKUSERUC); do $(SHELL) Package.sh $$p update; done
 
-package-overwrite po:
+package-overwrite:
 	@for p in $(PACKAGEUC); do $(SHELL) Package.sh $$p overwrite; done
 	@echo ''
 	@for p in $(PACKUSERUC); do $(SHELL) Package.sh $$p overwrite; done
 
-package-diff:
+package-diff pd:
 	@for p in $(PACKAGEUC); do $(SHELL) Package.sh $$p diff; done
 	@echo ''
 	@for p in $(PACKUSERUC); do $(SHELL) Package.sh $$p diff; done
diff --git a/src/group.cpp b/src/group.cpp
index a39f65ca47..74e0f8c88f 100644
--- a/src/group.cpp
+++ b/src/group.cpp
@@ -439,8 +439,13 @@ void Group::assign(int narg, char **arg)
   } else if (strcmp(arg[1],"dynamic") == 0) {
 
     if (narg < 4) error->all(FLERR,"Illegal group command");
+    if (strcmp(arg[0],arg[2]) == 0) 
+      error->all(FLERR,"Group dynamic cannot reference itself");
+    if (find(arg[2]) < 0) 
+      error->all(FLERR,"Group dynamic parent group does not exist");
+    if (igroup = 0) error->all(FLERR,"Group all cannot be made dynamic");
 
-    // if group is already dynamic, delete current FixGroup
+    // if group is already dynamic, delete existing FixGroup
 
     if (dynamic[igroup]) {
       int n = strlen("GROUP_") + strlen(names[igroup]) + 1;