Index: lib/Makefile
===================================================================
--- lib/Makefile
+++ lib/Makefile
@@ -183,8 +183,8 @@
     ${MACHINE_CPUARCH} == "arm" || ${MACHINE_CPUARCH} == "i386" || \
     ${MACHINE_CPUARCH} == "powerpc")
 _libclang_rt=	libclang_rt
-.elif ${MK_ASAN} != "no" || ${MK_UBSAN} != "no"
-.error "Requested build with sanitizers but cannot build runtime libraries!"
+.elif (${MK_ASAN} != "no" || ${MK_UBSAN} != "no") && .make(all)
+.error Requested build with sanitizers but cannot build runtime libraries!
 .endif
 
 .if ${MK_CXX} != "no"
Index: share/mk/bsd.sanitizer.mk
===================================================================
--- share/mk/bsd.sanitizer.mk
+++ share/mk/bsd.sanitizer.mk
@@ -23,7 +23,7 @@
 .endif # ${MK_UBSAN} == "yes"
 
 .if !defined(BOOTSTRAPPING) && ${_use_sanitizers} != "no" && \
-    ${COMPILER_TYPE} != "clang"
+    ${COMPILER_TYPE} != "clang" && .make(all)
 .error "Sanitizer instrumentation currently only supported with clang"
 .endif