diff --git a/ChangeLog b/ChangeLog
index 026f1d6b9e..9ef062f6c0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2019-08-15  Richard Henderson  <rth@twiddle.net>
+
+	* sysdeps/unix/sysv/linux/alpha/kernel-features.h (__NR_shmat):
+	Do not redefine.
+	* sysdeps/unix/sysv/linux/alpha/sysdep.h (__NR_osf_shmat):
+	Do not redefine.
+
 2019-07-15  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	[BZ #24699]
diff --git a/sysdeps/unix/sysv/linux/alpha/kernel-features.h b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
index 46178c5636..fc8407c8ab 100644
--- a/sysdeps/unix/sysv/linux/alpha/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/alpha/kernel-features.h
@@ -26,8 +26,10 @@
 #undef __ASSUME_STATFS64
 #define __ASSUME_STATFS64 0
 
-/* Alpha defines SysV ipc shmat syscall with a different name.  */
-#define __NR_shmat __NR_osf_shmat
+/* Alpha used to define SysV ipc shmat syscall with a different name.  */
+#ifndef __NR_shmat
+# define __NR_shmat __NR_osf_shmat
+#endif
 
 #define __ASSUME_RECV_SYSCALL	1
 #define __ASSUME_SEND_SYSCALL	1
diff --git a/sysdeps/unix/sysv/linux/alpha/sysdep.h b/sysdeps/unix/sysv/linux/alpha/sysdep.h
index dcf2d1e3d7..d61d4df550 100644
--- a/sysdeps/unix/sysv/linux/alpha/sysdep.h
+++ b/sysdeps/unix/sysv/linux/alpha/sysdep.h
@@ -51,7 +51,9 @@
  * Some syscalls no Linux program should know about:
  */
 #define __NR_osf_sigprocmask	 48
-#define __NR_osf_shmat		209
+#ifndef __NR_osf_shmat
+# define __NR_osf_shmat		209
+#endif
 #define __NR_osf_getsysinfo	256
 #define __NR_osf_setsysinfo	257