diff --git a/BaseTools/Source/Python/GenFds/FfsInfStatement.py b/BaseTools/Source/Python/GenFds/FfsInfStatement.py
index 6550d939d4..ec9713484e 100644
--- a/BaseTools/Source/Python/GenFds/FfsInfStatement.py
+++ b/BaseTools/Source/Python/GenFds/FfsInfStatement.py
@@ -93,7 +93,7 @@ class FfsInfStatement(FfsInfStatementClassObject):
 
                 if ModuleType != SUP_MODULE_USER_DEFINED and ModuleType != SUP_MODULE_HOST_APPLICATION:
                     for LibraryClass in PlatformDataBase.LibraryClasses.GetKeys():
-                        if LibraryClass.startswith("NULL") and PlatformDataBase.LibraryClasses[LibraryClass, ModuleType]:
+                        if LibraryClass.startswith("NULL") and LibraryClass[4:].isdigit() and PlatformDataBase.LibraryClasses[LibraryClass, ModuleType]:
                             self.InfModule.LibraryClasses[LibraryClass] = PlatformDataBase.LibraryClasses[LibraryClass, ModuleType]
 
                 StrModule = str(self.InfModule)
@@ -101,7 +101,7 @@ class FfsInfStatement(FfsInfStatementClassObject):
                 if StrModule in PlatformDataBase.Modules:
                     PlatformModule = PlatformDataBase.Modules[StrModule]
                     for LibraryClass in PlatformModule.LibraryClasses:
-                        if LibraryClass.startswith("NULL"):
+                        if LibraryClass.startswith("NULL") and LibraryClass[4:].isdigit():
                             self.InfModule.LibraryClasses[LibraryClass] = PlatformModule.LibraryClasses[LibraryClass]
 
                 DependencyList = [self.InfModule]
diff --git a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
index 8bb6553c6f..6ad7a3b940 100644
--- a/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
+++ b/BaseTools/Source/Python/Workspace/WorkspaceCommon.py
@@ -102,12 +102,12 @@ def GetModuleLibInstances(Module, Platform, BuildDatabase, Arch, Target, Toolcha
     #
     if Module.ModuleType != SUP_MODULE_USER_DEFINED:
         for LibraryClass in Platform.LibraryClasses.GetKeys():
-            if LibraryClass.startswith("NULL") and Platform.LibraryClasses[LibraryClass, Module.ModuleType]:
+            if LibraryClass.startswith("NULL") and LibraryClass[4:].isdigit() and Platform.LibraryClasses[LibraryClass, Module.ModuleType]:
                 Module.LibraryClasses[LibraryClass] = Platform.LibraryClasses[LibraryClass, Module.ModuleType]
 
     # add forced library instances (specified in module overrides)
     for LibraryClass in Platform.Modules[str(Module)].LibraryClasses:
-        if LibraryClass.startswith("NULL"):
+        if LibraryClass.startswith("NULL") and LibraryClass[4:].isdigit():
             Module.LibraryClasses[LibraryClass] = Platform.Modules[str(Module)].LibraryClasses[LibraryClass]
 
     # EdkII module
@@ -123,7 +123,7 @@ def GetModuleLibInstances(Module, Platform, BuildDatabase, Arch, Target, Toolcha
     while len(LibraryConsumerList) > 0:
         M = LibraryConsumerList.pop()
         for LibraryClassName in M.LibraryClasses:
-            if LibraryClassName.startswith("NULL") and bool(M.LibraryClass):
+            if LibraryClassName.startswith("NULL") and LibraryClassName[4:].isdigit() and bool(M.LibraryClass):
                 continue
             if LibraryClassName not in LibraryInstance:
                 # override library instance for this module
@@ -141,7 +141,7 @@ def GetModuleLibInstances(Module, Platform, BuildDatabase, Arch, Target, Toolcha
 
                 LibraryModule = BuildDatabase[LibraryPath, Arch, Target, Toolchain]
                 # for those forced library instance (NULL library), add a fake library class
-                if LibraryClassName.startswith("NULL"):
+                if LibraryClassName.startswith("NULL") and LibraryClassName[4:].isdigit():
                     LibraryModule.LibraryClass.append(LibraryClassObject(LibraryClassName, [ModuleType]))
                 elif LibraryModule.LibraryClass is None \
                      or len(LibraryModule.LibraryClass) == 0 \