diff --git a/src/Fetch.sh b/src/Fetch.sh
new file mode 100755
index 0000000000..ef60a41cda
--- /dev/null
+++ b/src/Fetch.sh
@@ -0,0 +1,40 @@
+# transparently fetch external files for a given package
+
+fetch_potentials() {
+    pdir="$1"
+    shift
+
+    type curl > /dev/null 2>&1 && have_curl=1 || have_curl=0
+    type wget > /dev/null 2>&1 && have_wget=1 || have_wget=0
+    if [ $have_curl -ne 1 ] && [ $have_wget -ne 1 ]
+    then \
+        echo "Need 'curl' or 'wget' to fetch external potential files"
+        return
+    fi
+
+    while [ $# -gt 1 ]
+    do \
+        file=$1; sum=$2
+        shift; shift
+
+        echo ${sum} ${pdir}/${file} | md5sum -c - > /dev/null 2>&1 \
+            && need_fetch=0 || need_fetch=1
+        if [ ${need_fetch} -eq 1 ]
+        then \
+            url="https://download.lammps.org/potentials/${file}.${sum}"
+            echo "Fetching external potential file ${file} from ${url}"
+            if [ ${have_curl} ]
+            then \
+                curl -L -o ${pdir}/${file} ${url}
+            elif [ ${have_wget} ]
+            then \
+                wget -O ${pdir}/${file} ${url}
+            fi
+        fi
+   done
+}
+
+if [ -f "$1/potentials.txt" ]
+then
+    fetch_potentials "$1/../../potentials" `sed -e 's/#.*$//' "$1/potentials.txt"`
+fi
diff --git a/src/Makefile b/src/Makefile
index a78068e092..5692a111c5 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -280,7 +280,7 @@ install-python:
 tar:
 	@cd STUBS; $(MAKE) clean
 	@cd ..; tar cvzf src/$(ROOT)_src.tar.gz \
-	  src/Make* src/Package.sh src/Depend.sh src/Install.sh \
+	  src/Make* src/Package.sh src/Depend.sh src/Install.sh src/Fetch.sh \
 	  src/MAKE src/DEPEND src/*.cpp src/*.h src/STUBS \
 	  $(patsubst %,src/%,$(PACKAGEUC)) $(patsubst %,src/%,$(PACKUSERUC)) \
           --exclude=*/.svn
@@ -369,6 +369,7 @@ yes-%:
 	  cd $(YESDIR); $(SHELL) ../Install.sh 1; cd ..; \
 		$(SHELL) Depend.sh $(YESDIR) 1; \
 	fi;
+	@$(SHELL) Fetch.sh $(YESDIR)
 
 no-%:
 	@if [ ! -e $(NODIR) ]; then \
diff --git a/src/USER-MISC/potentials.txt b/src/USER-MISC/potentials.txt
new file mode 100644
index 0000000000..4d4120a2a2
--- /dev/null
+++ b/src/USER-MISC/potentials.txt
@@ -0,0 +1,3 @@
+# list of potential files to be fetched when this package is installed
+# potential file  md5sum
+C_10_10.mesocnt 028de73ec828b7830d762702eda571c1