diff --git a/EdkModulePkg/Bus/Pci/AtapiPassThru/Dxe/AtapiPassThru.h b/EdkModulePkg/Bus/Pci/AtapiPassThru/Dxe/AtapiPassThru.h
index 659b37c876..fda5736878 100644
--- a/EdkModulePkg/Bus/Pci/AtapiPassThru/Dxe/AtapiPassThru.h
+++ b/EdkModulePkg/Bus/Pci/AtapiPassThru/Dxe/AtapiPassThru.h
@@ -21,7 +21,7 @@
 ///
 /// bit definition
 ///
-#define bit(a)        1 << (a)
+#define bit(a)        (1 << (a))
 
 #define MAX_TARGET_ID 4