diff --git a/share/mk/bsd.lib.mk b/share/mk/bsd.lib.mk
index 5de74b6fa05..aaac0b68d98 100644
--- a/share/mk/bsd.lib.mk
+++ b/share/mk/bsd.lib.mk
@@ -108,7 +108,8 @@ CXXFLAGS+= -ftrivial-auto-var-init=pattern
 .endif
 .endif
 
-.include "bsd.sanitizer.mk"
+# bsd.sanitizer.mk is not installed, so don't require it (e.g. for ports).
+.sinclude "bsd.sanitizer.mk"
 
 .if ${MK_DEBUG_FILES} != "no" && empty(DEBUG_FLAGS:M-g) && \
     empty(DEBUG_FLAGS:M-gdwarf*)
diff --git a/share/mk/bsd.prog.mk b/share/mk/bsd.prog.mk
index 96d72daf261..4f00be19387 100644
--- a/share/mk/bsd.prog.mk
+++ b/share/mk/bsd.prog.mk
@@ -81,7 +81,8 @@ CXXFLAGS+= -ftrivial-auto-var-init=pattern
 .endif
 .endif
 
-.include "bsd.sanitizer.mk"
+# bsd.sanitizer.mk is not installed, so don't require it (e.g. for ports).
+.sinclude "bsd.sanitizer.mk"
 
 .if ${MACHINE_CPUARCH} == "riscv" && ${LINKER_FEATURES:Mriscv-relaxations} == ""
 CFLAGS += -mno-relax