diff --git a/host-manager b/host-manager
index 9290d5f..3725850 100644
--- a/host-manager
+++ b/host-manager
@@ -7,7 +7,11 @@ remusage="Usage: `basename $0` -remove host"
 case "$1" in
 -add)
   if [ $# -eq 3 ]; then
-    printf "$3\t$2\n" >> ${path}
+    if [[ -n $(grep "^$3.*[^A-Za-z0-9\.]$2$" hosts) ]]; then
+      echo "Duplicate address/host combination, ${path} unchanged."
+    else
+      printf "$3\t$2\n" >> ${path}
+    fi
   else
     echo $addusage;
   fi