diff --git a/stand/common/bootstrap.h b/stand/common/bootstrap.h
--- a/stand/common/bootstrap.h
+++ b/stand/common/bootstrap.h
@@ -382,8 +382,4 @@
 int mount_currdev(struct env_var *, int, const void *);
 void set_currdev(const char *devname);
 
-#ifndef CTASSERT
-#define	CTASSERT(x)	_Static_assert(x, "compile-time assertion failed")
-#endif
-
 #endif /* !_BOOTSTRAP_H_ */
diff --git a/stand/efi/loader/arch/amd64/multiboot2.c b/stand/efi/loader/arch/amd64/multiboot2.c
--- a/stand/efi/loader/arch/amd64/multiboot2.c
+++ b/stand/efi/loader/arch/amd64/multiboot2.c
@@ -334,7 +334,7 @@
 	struct mb2hdr			*hdr;
 
 
-	CTASSERT(sizeof(header) <= PAGE_SIZE);
+	_Static_assert(sizeof(header) <= PAGE_SIZE, "header too big");
 
 	if ((md = file_findmetadata(fp,
 	    MODINFOMD_NOCOPY | MODINFOMD_MB2HDR)) == NULL) {
diff --git a/stand/i386/libi386/multiboot.c b/stand/i386/libi386/multiboot.c
--- a/stand/i386/libi386/multiboot.c
+++ b/stand/i386/libi386/multiboot.c
@@ -165,7 +165,7 @@
 	int				 error, mod_num;
 	struct xen_header		 header;
 
-	CTASSERT(sizeof(header) <= PAGE_SIZE);
+	_Static_assert(sizeof(header) <= PAGE_SIZE, "header too large for page");
 
 	/*
 	 * Don't pass the memory size found by the bootloader, the memory
diff --git a/stand/i386/loader/main.c b/stand/i386/loader/main.c
--- a/stand/i386/loader/main.c
+++ b/stand/i386/loader/main.c
@@ -51,14 +51,13 @@
 #include "libzfs.h"
 #endif
 
-CTASSERT(sizeof(struct bootargs) == BOOTARGS_SIZE);
-CTASSERT(offsetof(struct bootargs, bootinfo) == BA_BOOTINFO);
-CTASSERT(offsetof(struct bootargs, bootflags) == BA_BOOTFLAGS);
-CTASSERT(offsetof(struct bootinfo, bi_size) == BI_SIZE);
+_Static_assert(sizeof(struct bootargs) == BOOTARGS_SIZE, "Bootarg size bad");
+_Static_assert(offsetof(struct bootargs, bootinfo) == BA_BOOTINFO, "BA_BOOTINFO");
+_Static_assert(offsetof(struct bootargs, bootflags) == BA_BOOTFLAGS, "BA_BOOTFLAGS");
+_Static_assert(offsetof(struct bootinfo, bi_size) == BI_SIZE, "BI_SIZE");
 
 /* Arguments passed in from the boot1/boot2 loader */
 static struct bootargs *kargs;
-
 static uint32_t		initial_howto;
 static uint32_t		initial_bootdev;
 static struct bootinfo	*initial_bootinfo;