Index: uspace/lib/c/include/errno.h
===================================================================
--- uspace/lib/c/include/errno.h	(revision 84a04dd25d7cd11efb773bec08ac26839806991d)
+++ uspace/lib/c/include/errno.h	(revision 36082362a46bde6604dea1993953352a0edc3639)
@@ -65,4 +65,7 @@
 #define EEMPTY (-302)
 
+/** Negative acknowledgment. */
+#define ENAK (-303)
+
 /** An API function is called while another blocking function is in progress. */
 #define EINPROGRESS  (-10036)