diff --git a/srcpkgs/buffer/patches/musl-sem.patch b/srcpkgs/buffer/patches/musl-sem.patch
new file mode 100644
index 00000000000..d8a8d203f71
--- /dev/null
+++ b/srcpkgs/buffer/patches/musl-sem.patch
@@ -0,0 +1,13 @@
+The union semun is not defined in musl libc's sys/sem.h
+
+--- sem.c	2014-11-26 23:41:09.000000000 +0100
++++ sem.c	2016-08-12 10:14:48.225963726 +0200
+@@ -42,7 +42,7 @@
+  *
+  * mbuck@debian.org, 1999/08/29
+  */
+-#if defined(__GNU_LIBRARY__) && defined(_SEM_SEMUN_UNDEFINED)
++#if !defined(__GLIBC__) || (defined(__GNU_LIBRARY__) && defined(_SEM_SEMUN_UNDEFINED))
+ union semun {
+ 	int val;			/* value for SETVAL              */
+ 	struct semid_ds *buf;		/* buffer for IPC_STAT & IPC_SET */