diff --git a/BaseTools/Source/C/Makefiles/ms.common b/BaseTools/Source/C/Makefiles/ms.common
index a6bfea5036c4..06399dfb815c 100644
--- a/BaseTools/Source/C/Makefiles/ms.common
+++ b/BaseTools/Source/C/Makefiles/ms.common
@@ -42,14 +42,16 @@ BIN_PATH     = $(BASE_TOOLS_PATH)\Bin\Win32
 LIB_PATH     = $(BASE_TOOLS_PATH)\Lib\Win32
 SYS_BIN_PATH = $(EDK_TOOLS_PATH)\Bin\Win32
 SYS_LIB_PATH = $(EDK_TOOLS_PATH)\Lib\Win32
-!ENDIF
 
-!IF "$(HOST_ARCH)"=="X64"
+!ELSEIF "$(HOST_ARCH)"=="X64"
 ARCH_INCLUDE = $(SOURCE_PATH)\Include\X64
 BIN_PATH     = $(BASE_TOOLS_PATH)\Bin\Win64
 LIB_PATH     = $(BASE_TOOLS_PATH)\Lib\Win64
 SYS_BIN_PATH = $(EDK_TOOLS_PATH)\Bin\Win64
 SYS_LIB_PATH = $(EDK_TOOLS_PATH)\Lib\Win64
+
+!ELSE
+!ERROR "Unknown HOST_ARCH variable"
 !ENDIF
 
 CC = cl.exe