diff --git a/stl/CMakeLists.txt b/stl/CMakeLists.txt
index 7a93242a9bd..e39803c0106 100644
--- a/stl/CMakeLists.txt
+++ b/stl/CMakeLists.txt
@@ -419,7 +419,7 @@ set(CMAKE_SHARED_LINKER_FLAGS_DEBUG "")
 set(CMAKE_SHARED_LINKER_FLAGS_RELEASE "")
 
 # Toolset options must appear before add_library() for the options to take effect.
-add_compile_definitions(_CRTBLD _VCRT_ALLOW_INTERNALS _HAS_OLD_IOSTREAMS_MEMBERS=1)
+add_compile_definitions(_CRTBLD _HAS_OLD_IOSTREAMS_MEMBERS=1)
 
 # /Z7 for MSVC, /Zi for MASM
 set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT "Embedded")
diff --git a/stl/msbuild/stl_1/msvcp_1.settings.targets b/stl/msbuild/stl_1/msvcp_1.settings.targets
index 30d8178cbeb..03e2a3abe31 100644
--- a/stl/msbuild/stl_1/msvcp_1.settings.targets
+++ b/stl/msbuild/stl_1/msvcp_1.settings.targets
@@ -29,7 +29,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <LibOutputFileName>msvcprt_1$(BuildSuffix)$(ClrLibSuffix)</LibOutputFileName>
         <LibOutputFile>$(LibOutputFileName).lib</LibOutputFile>
 
-        <ClDefines>_VCRT_ALLOW_INTERNALS;$(ClDefines)</ClDefines>
         <ClDefines Condition="'$(MsvcpFlavor)' == 'app'">$(ClDefines);_CRT_APP</ClDefines>
 
         <UseMsvcrt>false</UseMsvcrt>
diff --git a/stl/msbuild/stl_2/msvcp_2.settings.targets b/stl/msbuild/stl_2/msvcp_2.settings.targets
index a5c2fd53b56..d70f43cf143 100644
--- a/stl/msbuild/stl_2/msvcp_2.settings.targets
+++ b/stl/msbuild/stl_2/msvcp_2.settings.targets
@@ -29,7 +29,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <LibOutputFileName>msvcprt_2$(BuildSuffix)$(ClrLibSuffix)</LibOutputFileName>
         <LibOutputFile>$(LibOutputFileName).lib</LibOutputFile>
 
-        <ClDefines>_VCRT_ALLOW_INTERNALS;$(ClDefines)</ClDefines>
         <ClDefines Condition="'$(MsvcpFlavor)' == 'app'">$(ClDefines);_CRT_APP</ClDefines>
 
         <UseMsvcrt>false</UseMsvcrt>
diff --git a/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets b/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
index 0f29c995877..ff8ede7dff0 100644
--- a/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
+++ b/stl/msbuild/stl_atomic_wait/msvcp_atomic_wait.settings.targets
@@ -29,7 +29,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <LibOutputFileName>msvcprt$(BuildSuffix)_atomic_wait$(ClrLibSuffix)</LibOutputFileName>
         <LibOutputFile>$(LibOutputFileName).lib</LibOutputFile>
 
-        <ClDefines>_VCRT_ALLOW_INTERNALS;$(ClDefines)</ClDefines>
         <ClDefines Condition="'$(MsvcpFlavor)' == 'app'">$(ClDefines);_CRT_APP</ClDefines>
 
         <UseMsvcrt>false</UseMsvcrt>
diff --git a/stl/msbuild/stl_base/libcp.settings.targets b/stl/msbuild/stl_base/libcp.settings.targets
index 0e03b8a714e..6a9ba43ead3 100644
--- a/stl/msbuild/stl_base/libcp.settings.targets
+++ b/stl/msbuild/stl_base/libcp.settings.targets
@@ -27,7 +27,7 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
     <PropertyGroup>
         <ClProgramDataBaseFileName>$(OutputLibPdbPath)$(OutputName)$(PdbVerName).pdb</ClProgramDataBaseFileName>
-        <ClDefines>$(ClDefines);_VCRT_ALLOW_INTERNALS;_ANNOTATE_STL</ClDefines>
+        <ClDefines>$(ClDefines);_ANNOTATE_STL</ClDefines>
     </PropertyGroup>
 
     <Import Project="$(MSBuildThisFileDirectory)\stl.files.settings.targets"/>
diff --git a/stl/msbuild/stl_base/msvcp.settings.targets b/stl/msbuild/stl_base/msvcp.settings.targets
index 825cf4929eb..dcfdb0903c8 100644
--- a/stl/msbuild/stl_base/msvcp.settings.targets
+++ b/stl/msbuild/stl_base/msvcp.settings.targets
@@ -32,7 +32,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <LibOutputFileName>msvcprt_base$(BuildSuffix)$(ClrLibSuffix)</LibOutputFileName>
         <LibOutputFile>$(LibOutputFileName).lib</LibOutputFile>
 
-        <ClDefines>_VCRT_ALLOW_INTERNALS;$(ClDefines)</ClDefines>
         <ClDefines Condition="'$(MsvcpFlavor)' == 'app'">$(ClDefines);_CRT_APP</ClDefines>
 
         <UseMsvcrt>false</UseMsvcrt>
diff --git a/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets b/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
index 6d1166d0606..5146d0dd0be 100644
--- a/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
+++ b/stl/msbuild/stl_codecvt_ids/msvcp_codecvt_ids.settings.targets
@@ -29,7 +29,6 @@ SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
         <LibOutputFileName>msvcprt$(BuildSuffix)_codecvt_ids$(ClrLibSuffix)</LibOutputFileName>
         <LibOutputFile>$(LibOutputFileName).lib</LibOutputFile>
 
-        <ClDefines>_VCRT_ALLOW_INTERNALS;$(ClDefines)</ClDefines>
         <ClDefines Condition="'$(MsvcpFlavor)' == 'app'">$(ClDefines);_CRT_APP</ClDefines>
 
         <UseMsvcrt>false</UseMsvcrt>
diff --git a/stl/src/excptptr.cpp b/stl/src/excptptr.cpp
index e866980fb1d..46cafd13e97 100644
--- a/stl/src/excptptr.cpp
+++ b/stl/src/excptptr.cpp
@@ -8,7 +8,7 @@
 
 #ifndef _VCRT_ALLOW_INTERNALS
 #define _VCRT_ALLOW_INTERNALS
-#endif // !defined(_VCRT_ALLOW_INTERNALS)
+#endif
 
 #include <Unknwn.h>
 #include <cstdlib> // for abort
diff --git a/stl/src/pplerror.cpp b/stl/src/pplerror.cpp
index 32fd0714c3f..afc48e23394 100644
--- a/stl/src/pplerror.cpp
+++ b/stl/src/pplerror.cpp
@@ -1,6 +1,10 @@
 // Copyright (c) Microsoft Corporation.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#ifndef _VCRT_ALLOW_INTERNALS
+#define _VCRT_ALLOW_INTERNALS
+#endif
+
 #include <ppltasks.h>
 
 #if defined(_CRT_APP) || defined(UNDOCKED_WINDOWS_UCRT)