diff --git a/test/MC/Disassembler/X86/missing-sib.txt b/test/MC/Disassembler/X86/missing-sib.txt
new file mode 100644
index 00000000000..814f68406d3
--- /dev/null
+++ b/test/MC/Disassembler/X86/missing-sib.txt
@@ -0,0 +1,4 @@
+# RUN: llvm-mc --disassemble %s -triple=x86_64-apple-darwin9 2>&1 | grep "invalid instruction encoding"
+
+# This instruction would decode as jmp32m if it didn't run out of bytes
+0xff 0x24