diff --git a/HpcMarkup.hs b/HpcMarkup.hs
index 46e17090f4d7b866237891756d74fdefecaa423f..dff6012cb00ef53e7e1a9858a2477b3d9c6688be 100644
--- a/HpcMarkup.hs
+++ b/HpcMarkup.hs
@@ -406,7 +406,7 @@ showTotalSummary modSummary =
    showSummary (expTicked modSummary) (expTotal modSummary) ++
   "</tr>\n"
 
-showSummary :: (Integral t) => t -> t -> String
+showSummary :: (Integral t, Show t) => t -> t -> String
 showSummary ticked total =
                 "<td align=\"right\">" ++ showP (percent ticked total) ++ "</td>" ++
                 "<td>" ++ show ticked ++ "/" ++ show total ++ "</td>" ++