diff --git a/ShellCheck/Analytics.hs b/ShellCheck/Analytics.hs
index c6da563..7ad172c 100644
--- a/ShellCheck/Analytics.hs
+++ b/ShellCheck/Analytics.hs
@@ -1115,11 +1115,13 @@ prop_checkArithmeticDeref10= verifyNot checkArithmeticDeref "(( a[\\$foo] ))"
 prop_checkArithmeticDeref11= verifyNot checkArithmeticDeref "a[$foo]=wee"
 prop_checkArithmeticDeref12= verify checkArithmeticDeref "for ((i=0; $i < 3; i)); do true; done"
 prop_checkArithmeticDeref13= verifyNot checkArithmeticDeref "(( $$ ))"
+prop_checkArithmeticDeref14= verifyNot checkArithmeticDeref "(( $! ))"
+prop_checkArithmeticDeref15= verifyNot checkArithmeticDeref "(( ${!var} ))"
 checkArithmeticDeref params t@(TA_Expansion _ [b@(T_DollarBraced id _)]) =
     unless (isException $ bracedString b) getWarning
   where
     isException [] = True
-    isException s = any (`elem` "/.:#%?*@$-") s || isDigit (head s)
+    isException s = any (`elem` "/.:#%?*@$-!") s || isDigit (head s)
     getWarning = fromMaybe noWarning . msum . map warningFor $ parents params t
     warningFor t =
         case t of