diff --git a/tests/test-highlighting.zsh b/tests/test-highlighting.zsh
index 6f7fa96..94c4152 100755
--- a/tests/test-highlighting.zsh
+++ b/tests/test-highlighting.zsh
@@ -61,7 +61,19 @@ fi
 [[ -n $results_filter ]] || { echo >&2 "Bail out! BUG setting \$results_filter"; exit 2 }
 
 # Load the main script.
+# While here, test that it doesn't eat aliases.
+print > >($results_filter | ${0:A:h}/tap-colorizer.zsh) -r -- "# global (driver) tests"
+print > >($results_filter | ${0:A:h}/tap-colorizer.zsh) -r -- "1..1"
+alias -- +plus=plus
+alias -- _other=other
+original_alias_dash_L_output="$(alias -L)"
 . ${0:h:h}/zsh-syntax-highlighting.zsh
+if [[ $original_alias_dash_L_output == $(alias -L) ]]; then
+  print -r -- "ok 1 # 'alias -- +foo=bar' is preserved"
+else
+  print -r -- "not ok 1 # 'alias -- +foo=bar' is preserved"
+  exit 1
+fi > >($results_filter | ${0:A:h}/tap-colorizer.zsh) 
 
 # Overwrite _zsh_highlight_add_highlight so we get the key itself instead of the style
 _zsh_highlight_add_highlight()