--- a/mfbt/tests/TestPoisonArea.cpp
+++ b/mfbt/tests/TestPoisonArea.cpp
@@ -128,16 +128,19 @@
 #elif defined __arm__ || defined _M_ARM
 #define RETURN_INSTR 0xE12FFF1E /* bx lr */
 
 // PPC has its own style of CPU-id #defines.  There is no Windows for
 // PPC as far as I know, so no _M_ variant.
 #elif defined _ARCH_PPC || defined _ARCH_PWR || defined _ARCH_PWR2
 #define RETURN_INSTR 0x4E800020 /* blr */
 
+#elif defined __m68k__
+#define RETURN_INSTR 0x4E754E75 /* rts; rts */
+
 #elif defined __sparc || defined __sparcv9
 #define RETURN_INSTR 0x81c3e008 /* retl */
 
 #elif defined __alpha
 #define RETURN_INSTR 0x6bfa8001 /* ret */
 
 #elif defined __hppa
 #define RETURN_INSTR 0xe840c002 /* bv,n r0(rp) */