diff --git a/libexec/rbenv-init b/libexec/rbenv-init
index 29daa10c..df2bf00c 100755
--- a/libexec/rbenv-init
+++ b/libexec/rbenv-init
@@ -71,13 +71,13 @@ commands=(`rbenv commands --sh`)
 IFS="|"
 cat <<EOS
 function rbenv () {
-  command=\$1;
+  command="\$1";
   shift;
-  case \$command in
+  case "\$command" in
   ${commands[*]})
-    eval \`rbenv sh-\$command \$@\`;;
+    eval \`rbenv "sh-\$command" "\$@"\`;;
   *)
-    command rbenv \$command \$@;;
+    command rbenv "\$command" "\$@";;
   esac;
 };
 EOS