diff --git a/libs/test-foreign.scm b/libs/test-foreign.scm
index 7a00aa43..9628b183 100644
--- a/libs/test-foreign.scm
+++ b/libs/test-foreign.scm
@@ -32,7 +32,13 @@
 )
 
 ;; Must be top-level
-(c-define scm-strlen "int" "strlen" string)
+
+TODO: support custom types (arg and ret) for c-define.
+      Also need to be able to support arg/ret convert optional type arguments
+      Would need to generate scheme wrappers to handle these conversions
+
+(c-define scm-strlen my-integer "strlen" string)
+;(c-define scm-strlen "int" "strlen" string)
 (c-define scm-strlend double "strlen" string)
 
 (test-group "foreign lambda"