diff --git a/compiler-rt/lib/ubsan/ubsan_platform.h b/compiler-rt/lib/ubsan/ubsan_platform.h
--- a/compiler-rt/lib/ubsan/ubsan_platform.h
+++ b/compiler-rt/lib/ubsan/ubsan_platform.h
@@ -14,7 +14,7 @@
 
 // Other platforms should be easy to add, and probably work as-is.
 #if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__) ||        \
-    defined(__NetBSD__) || \
+    defined(__NetBSD__) || defined(__DragonFly__) \
     (defined(__sun__) && defined(__svr4__)) || \
     defined(_WIN32) || defined(__Fuchsia__) || defined(__rtems__)
 # define CAN_SANITIZE_UB 1