diff --git a/Library/Homebrew/cmd/shellenv.sh b/Library/Homebrew/cmd/shellenv.sh
index 257fec7e8e..d6b9a86385 100644
--- a/Library/Homebrew/cmd/shellenv.sh
+++ b/Library/Homebrew/cmd/shellenv.sh
@@ -29,7 +29,7 @@ homebrew-shellenv() {
       echo "export HOMEBREW_REPOSITORY=\"$HOMEBREW_REPOSITORY\";"
       echo "export PATH=\"$HOMEBREW_PREFIX/bin:$HOMEBREW_PREFIX/sbin\${PATH+:\$PATH}\";"
       echo "export MANPATH=\"$HOMEBREW_PREFIX/share/man\${MANPATH+:\$MANPATH}:\";"
-      echo "export INFOPATH=\"$HOMEBREW_PREFIX/share/info:\${INFOPATH}\";"
+      echo "export INFOPATH=\"$HOMEBREW_PREFIX/share/info:\${INFOPATH:-}\";"
       ;;
   esac
 }