diff --git a/sys/rump/Makefile.rump b/sys/rump/Makefile.rump
index cdbaef327bc3..066101c04a06 100644
--- a/sys/rump/Makefile.rump
+++ b/sys/rump/Makefile.rump
@@ -24,6 +24,12 @@ CPPFLAGS+=	-D_RUMPKERNEL -I${RUMPTOP}/librump/rumpkern
 # aborts after kern_assert on NULL pointer checks.
 CFLAGS+=    ${${ACTIVE_CC} == "gcc":? -fno-delete-null-pointer-checks :}
 
+# NULL + 0 arithmetic raises LLVM UBSan warnings, specially in sys/pslist.h
+# in the type-safe macros _PSLIST_VALIDATE_PTRS and _PSLIST_VALIDATE_CONTAINER.
+.if ${MKSANITIZER:Uno} == "yes" || ${MKLIBCSANITIZER:Uno} == "yes"
+CFLAGS+=    ${${ACTIVE_CC} == "clang":? -fno-delete-null-pointer-checks :}
+.endif
+
 # Define baseline cpu for mips ports, required for
 # rumpcomp_sync_icache() hypercall.
 .if !empty(MACHINE_ARCH:Mmips*)