diff --git a/rc/filetype/sh.kak b/rc/filetype/sh.kak
index 55ae3251..06565a8d 100644
--- a/rc/filetype/sh.kak
+++ b/rc/filetype/sh.kak
@@ -22,12 +22,14 @@ provide-module sh %§
 
 add-highlighter shared/sh regions
 add-highlighter shared/sh/code default-region group
+add-highlighter shared/sh/arithmetic region -recurse \(.*?\( (\$|(?<=for)\h*)\(\( \)\) group
 add-highlighter shared/sh/double_string region  %{(?<!\\)(?:\\\\)*\K"} %{(?<!\\)(?:\\\\)*"} group
 add-highlighter shared/sh/single_string region %{(?<!\\)(?:\\\\)*\K'} %{'} fill string
 add-highlighter shared/sh/expansion region -recurse (?<!\\)(?:\\\\)*\K\$\{ (?<!\\)(?:\\\\)*\K\$\{ \}|\n fill value
 add-highlighter shared/sh/comment region (?<!\\)(?:\\\\)*(?:^|\h)\K# '$' fill comment
 add-highlighter shared/sh/heredoc region -match-capture '<<-?\h*''?(\w+)''?' '^\t*(\w+)$' fill string
 
+add-highlighter shared/sh/arithmetic/expansion ref sh/double_string/expansion
 add-highlighter shared/sh/double_string/fill fill string
 
 evaluate-commands %sh{