diff --git a/Unix/UtilIO.icl b/Unix/UtilIO.icl
index 0680ee4a63986c46c75a551299423e8df1fe1b13..104127d2bef7078e4c0103720cebdc6b6c357b10 100644
--- a/Unix/UtilIO.icl
+++ b/Unix/UtilIO.icl
@@ -93,7 +93,7 @@ load_long p = code {
 
 realpath :: !{#Char} !Int -> Int;
 realpath path resolved_path = code {
-	ccall realpath "sI:I"
+	ccall realpath "sp:p"
 }
 
 free :: !Int -> Int;