--- include/pub_tool_machine.h.orig
+++ include/pub_tool_machine.h
@@ -32,14 +32,14 @@
 #include "pub_tool_basics.h"           // ThreadID
 #include "libvex.h"                    // VexArchInfo
 
-#if defined(VGP_x86_linux) || defined(VGP_x86_solaris) || defined(VGP_x86_freebsd)
+#if defined(VGP_x86_linux) || defined(VGP_x86_solaris) || defined(VGP_x86_freebsd) || defined(VGP_x86_openbsd)
 #  define VG_MIN_INSTR_SZB          1  // min length of native instruction
 #  define VG_MAX_INSTR_SZB         16  // max length of native instruction
 #  define VG_CLREQ_SZB             14  // length of a client request, may
                                        //   be larger than VG_MAX_INSTR_SZB
 #  define VG_STACK_REDZONE_SZB      0  // number of addressable bytes below %RSP
 
-#elif defined(VGP_amd64_linux) || defined(VGP_amd64_solaris) || defined(VGP_amd64_freebsd)
+#elif defined(VGP_amd64_linux) || defined(VGP_amd64_solaris) || defined(VGP_amd64_freebsd) || defined(VGP_amd64_openbsd)
 #  define VG_MIN_INSTR_SZB          1
 #  define VG_MAX_INSTR_SZB         16
 #  define VG_CLREQ_SZB             19