Index: Source/bmalloc/bmalloc/VMAllocate.h
--- Source/bmalloc/bmalloc/VMAllocate.h.orig
+++ Source/bmalloc/bmalloc/VMAllocate.h
@@ -299,7 +299,7 @@ inline void vmDeallocatePhysicalPages(void* p, size_t 
     vmValidatePhysical(p, vmSize);
 #if BOS(DARWIN)
     SYSCALL(madvise(p, vmSize, MADV_FREE_REUSABLE));
-#elif BOS(FREEBSD)
+#elif (BOS(FREEBSD) || BOS(OPENBSD))
     SYSCALL(madvise(p, vmSize, MADV_FREE));
 #else
     SYSCALL(madvise(p, vmSize, MADV_DONTNEED));
