diff --git a/BaseTools/Conf/build_rule.template b/BaseTools/Conf/build_rule.template
index f1edf3a2f4..e5467cc455 100644
--- a/BaseTools/Conf/build_rule.template
+++ b/BaseTools/Conf/build_rule.template
@@ -194,7 +194,7 @@
 
 [Nasm-Assembly-Code-File.COMMON.COMMON]
     <InputFile>
-        ?.nasm, ?.Nasm, ?.NASM
+        ?.nasm
 
     <ExtraDependency>
         $(MAKE_FILE)
@@ -479,7 +479,7 @@
 
 [Nasm-to-Binary-Code-File]
     <InputFile>
-        ?.nasmb, ?.NASMB
+        ?.nasmb
 
     <ExtraDependency>
         $(MAKE_FILE)
diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template
index ad34a3d6ee..fd7b4b55e8 100644
--- a/BaseTools/Conf/tools_def.template
+++ b/BaseTools/Conf/tools_def.template
@@ -6276,7 +6276,7 @@ NOOPT_MYTOOLS_IPF_DLINK_FLAGS            = /NOLOGO /NODEFAULTLIB /LTCG /DLL /OPT
 #   XCODE32         - Xcode 3.2 Tools (Snow Leopard)
 *_XCODE32_*_*_FAMILY            = GCC
 *_XCODE32_*_*_BUILDRULEFAMILY   = XCODE
-*_XCODE32_*_*_BUILDRULEORDER    = S s nasm Nasm NASM
+*_XCODE32_*_*_BUILDRULEORDER    = S s nasm
 
 
 *_XCODE32_*_ASL_PATH          = /usr/bin/iasl
@@ -6386,7 +6386,7 @@ RELEASE_XCODE32_ARM_CC_FLAGS   = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) -mthumb-inter
 #   CLANG         - clang that produce Mach-O with EFI x86_64 ABI
 *_XCLANG_*_*_FAMILY            = GCC
 *_XCLANG_*_*_BUILDRULEFAMILY   = XCODE
-*_XCLANG_*_*_BUILDRULEORDER    = S s nasm Nasm NASM
+*_XCLANG_*_*_BUILDRULEORDER    = S s nasm
 
 *_XCLANG_*_ASL_PATH          = /usr/bin/iasl
 
@@ -6450,7 +6450,7 @@ RELEASE_XCLANG_X64_CC_FLAGS   = -ccc-host-triple x86_64-pc-win32-macho -c    -Os
 
 *_XCODE5_*_*_FAMILY            = GCC
 *_XCODE5_*_*_BUILDRULEFAMILY   = XCODE
-*_XCODE5_*_*_BUILDRULEORDER    = S s nasm Nasm NASM
+*_XCODE5_*_*_BUILDRULEORDER    = S s nasm
 
 *_XCODE5_*_ASL_PATH          = /usr/bin/iasl
 
@@ -6947,4 +6947,4 @@ RELEASE_ARMLINUXGCC_AARCH64_CC_FLAGS = $(ARCHCC_FLAGS) $(PLATFORM_FLAGS) DEF(GCC
 #################
 # Build rule order
 #################
-*_*_*_*_BUILDRULEORDER = nasm Nasm NASM asm Asm ASM S s
+*_*_*_*_BUILDRULEORDER = nasm asm Asm ASM S s