diff --git a/arch/x86/defs.h b/arch/x86/defs.h
index 63d2435..432ccc8 100644
--- a/arch/x86/defs.h
+++ b/arch/x86/defs.h
@@ -1,21 +1,59 @@
 #ifndef __ARCH_X86_DEFS_H
 #define __ARCH_X86_DEFS_H
 
+#ifndef _GNU_SOURCE
 #ifndef REG_GS
 # define REG_GS		(0)
+#endif
+
+#ifndef REG_FS
 # define REG_FS		(1)
+#endif
+
+#ifndef REG_ES
 # define REG_ES		(2)
+#endif
+
+#ifndef REG_DS
 # define REG_DS		(3)
+#endif
+
+#ifndef REG_EDI
 # define REG_EDI	(4)
+#endif
+
+#ifndef REG_ESI
 # define REG_ESI	(5)
+#endif
+
+#ifndef REG_EBP
 # define REG_EBP	(6)
+#endif
+
+#ifndef REG_ESP
 # define REG_ESP	(7)
+#endif
+
+#ifndef REG_EBX
 # define REG_EBX	(8)
+#endif
+
+#ifndef REG_EDX
 # define REG_EDX	(9)
+#endif
+
+#ifndef REG_ECX
 # define REG_ECX	(10)
+#endif
+
+#ifndef REG_EAX
 # define REG_EAX	(11)
+#endif
+
+#ifndef REG_EIP
 # define REG_EIP	(14)
 #endif
+#endif
 
 #define REG_SZ		(4)
 
diff --git a/arch/x86/makecontext.c b/arch/x86/makecontext.c
index bad91f1..fc292f9 100644
--- a/arch/x86/makecontext.c
+++ b/arch/x86/makecontext.c
@@ -16,13 +16,14 @@
 #include <stdarg.h>
 #include <string.h>
 #include <stdint.h>
+#include "defs.h"
 
 
 extern void libucontext_trampoline(void);
 
 
 void
-libucontext_makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
+libucontext_makecontext(libucontext_ucontext_t *ucp, void (*func)(void), int argc, ...)
 {
 	libucontext_greg_t *sp, *argp;
 	va_list va;