Index: uspace/lib/c/include/futex.h
===================================================================
--- uspace/lib/c/include/futex.h	(revision 74a2a2dd5a514e8b4e53569250bf8f7dbee84d26)
+++ uspace/lib/c/include/futex.h	(revision 897fd8f11ec6c9c4a63697b4ccc6ab67c8be92f2)
@@ -37,4 +37,5 @@
 
 #include <atomic.h>
+#include <errno.h>
 #include <libc.h>
 
@@ -121,6 +122,6 @@
  *
  * @return ENOENT if there is no such virtual address.
- * @return Zero in the uncontended case.
- * @return Otherwise one of ESYNCH_OK_ATOMIC or ESYNCH_OK_BLOCKED.
+ * @return EOK on success.
+ * @return Error code from <errno.h> otherwise.
  *
  */
@@ -130,5 +131,5 @@
 		return __SYSCALL1(SYS_FUTEX_SLEEP, (sysarg_t) &futex->val.count);
 	
-	return 0;
+	return EOK;
 }
 
@@ -138,5 +139,6 @@
  *
  * @return ENOENT if there is no such virtual address.
- * @return Zero in the uncontended case.
+ * @return EOK on success.
+ * @return Error code from <errno.h> otherwise.
  *
  */
@@ -146,5 +148,5 @@
 		return __SYSCALL1(SYS_FUTEX_WAKEUP, (sysarg_t) &futex->val.count);
 	
-	return 0;
+	return EOK;
 }