diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index c4afe40..a90e8ca 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -3304,7 +3304,7 @@
 }
 }
 
-def : InstAlias<"dmb", (DMB 0xf)>;
+def : InstAlias<"dmb", (DMB 0xf)>, Requires<[IsARM, HasDB]>;
 
 def DSB : AInoP<(outs), (ins memb_opt:$opt), MiscFrm, NoItinerary,
                 "dsb", "\t$opt", []>,