diff --git a/sys/compat/linux/linux_mmap.c b/sys/compat/linux/linux_mmap.c
index 70d274c5aca..a81a02ac8ae 100644
--- a/sys/compat/linux/linux_mmap.c
+++ b/sys/compat/linux/linux_mmap.c
@@ -228,6 +228,11 @@ int
 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
 {
 
+	/* XXX Ignore PROT_GROWSDOWN and PROT_GROWSUP for now. */
+	prot &= ~(LINUX_PROT_GROWSDOWN | LINUX_PROT_GROWSUP);
+	if ((prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) != 0)
+		return (EINVAL);
+
 #if defined(__amd64__)
 	linux_fixup_prot(td, &prot);
 #endif
diff --git a/sys/compat/linux/linux_mmap.h b/sys/compat/linux/linux_mmap.h
index a27d99d989d..a694dc05799 100644
--- a/sys/compat/linux/linux_mmap.h
+++ b/sys/compat/linux/linux_mmap.h
@@ -41,6 +41,8 @@
 #define	LINUX_MAP_ANON		0x0020
 #define	LINUX_MAP_GROWSDOWN	0x0100
 
+#define	LINUX_PROT_GROWSDOWN	0x01000000
+#define	LINUX_PROT_GROWSUP	0x02000000
 
 int linux_mmap_common(struct thread *, uintptr_t, size_t, int, int,
 			int, off_t);