diff --git a/src/ipc/lowlevel.cr b/src/ipc/lowlevel.cr
index 71bef9d..d9681cd 100644
--- a/src/ipc/lowlevel.cr
+++ b/src/ipc/lowlevel.cr
@@ -124,7 +124,7 @@ lib LibIPC
 	fun ipc_provide_fd (sock : LibC::Int, fd : LibC::Int ) : IPCError
 
 	# To change the type of a fd.
-	fun ipc_ctx_fd_type(Ctx*, LibC::Int, LibIPC::ConnectionType) : IPCError
+	fun ipc_ctx_fd_type(Ctx*, LibC::Int, LibIPC::ConnectionType) : LibC::Int
 
 	enum IPCCB
 		NoError       #