Index: stand/Makefile.inc
===================================================================
--- stand/Makefile.inc
+++ stand/Makefile.inc
@@ -1,8 +1,10 @@
 # $FreeBSD$
 
-# Sanitizers won't work for stand
+.if !defined(_USE_DEFAULT_USERSPACE_LIBS)
+# Sanitizers won't work for stand (except for userboot/test).
 MK_ASAN:=no
 MK_UBSAN:=no
+.endif
 
 SUBDIR_PARALLEL=	yes
 
Index: stand/userboot/test/Makefile
===================================================================
--- stand/userboot/test/Makefile
+++ stand/userboot/test/Makefile
@@ -1,5 +1,10 @@
 # $FreeBSD$
 
+# Unlike the other programs in stand this links the normal userspace libraries
+# so we have to ensure MK_ASAN/MK_UBSAN matches the default to avoid linker
+# errors (this assignment prevents stand/Makefile.inc from setting MK_ASAN=no).
+_USE_DEFAULT_USERSPACE_LIBS=yes
+
 .include <bsd.init.mk>
 
 PROG=		test