diff --git a/src/bindings.cr b/src/bindings.cr
index 7127fc5..2224ac1 100644
--- a/src/bindings.cr
+++ b/src/bindings.cr
@@ -47,5 +47,5 @@ lib LibIPC
   # One of the callbacks can be "NULL" to keep the default callback, thus changing only input or output operations.
   fun switch_callbacks = ipc_set_switch_callbacks (Void*, LibC::Int,
     (LibC::Int, LibC::Char*, LibC::UInt64T* -> LibC::Char),
-    (LibC::Int, LibC::Char*, LibC::UInt64T  -> LibC::Char));
+    (LibC::Int, LibC::Char*, LibC::UInt64T  -> LibC::Char)) : LibC::Int
 end