diff --git a/MsCorePkg/Include/Library/DeviceSpecificBusInfoLib.h b/MsCorePkg/Include/Library/DeviceSpecificBusInfoLib.h
index add2eefc89..25779a5711 100644
--- a/MsCorePkg/Include/Library/DeviceSpecificBusInfoLib.h
+++ b/MsCorePkg/Include/Library/DeviceSpecificBusInfoLib.h
@@ -12,6 +12,9 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
 
+#ifndef DEVICE_SPECIFIC_BUS_INFO_LIB_H_
+#define DEVICE_SPECIFIC_BUS_INFO_LIB_H_
+
 typedef enum {
   Ignore,     // Do not check link speed
   Gen1,       // 2.5 GT/s
@@ -72,3 +75,5 @@ ProcessPciDeviceResults (
   IN  UINTN                    ResultCount,
   IN  DEVICE_PCI_CHECK_RESULT  *Results
   );
+
+#endif
diff --git a/MsWheaPkg/HwhMenu/CreatorIDParser.h b/MsWheaPkg/HwhMenu/CreatorIDParser.h
index 1c96655909..ed5204f28f 100644
--- a/MsWheaPkg/HwhMenu/CreatorIDParser.h
+++ b/MsWheaPkg/HwhMenu/CreatorIDParser.h
@@ -8,6 +8,9 @@ Copyright (c) Microsoft Corporation. All rights reserved.
 SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
+#ifndef CREATOR_ID_PARSER_H_
+#define CREATOR_ID_PARSER_H_
+
 /**
  *  Parses the Creator ID which, for now, just prints the GUID
  *
@@ -19,3 +22,5 @@ VOID
 ParseCreatorID (
   IN CONST EFI_GUID  *CreatorID
   );
+
+#endif
diff --git a/MsWheaPkg/HwhMenu/PlatformIDParser.h b/MsWheaPkg/HwhMenu/PlatformIDParser.h
index 0da55f7f35..8a198b99c0 100644
--- a/MsWheaPkg/HwhMenu/PlatformIDParser.h
+++ b/MsWheaPkg/HwhMenu/PlatformIDParser.h
@@ -9,6 +9,9 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
 
 **/
 
+#ifndef PLATFORM_ID_PARSER_H_
+#define PLATFORM_ID_PARSER_H_
+
 /**
  *  Parses the Platform/Source ID
  *
@@ -20,3 +23,5 @@ VOID
 ParseSourceID (
   IN CONST EFI_GUID  *SourceID
   );
+
+#endif
diff --git a/MsWheaPkg/Include/Library/CheckHwErrRecHeaderLib.h b/MsWheaPkg/Include/Library/CheckHwErrRecHeaderLib.h
index f88e9e963d..883cc78661 100644
--- a/MsWheaPkg/Include/Library/CheckHwErrRecHeaderLib.h
+++ b/MsWheaPkg/Include/Library/CheckHwErrRecHeaderLib.h
@@ -4,6 +4,9 @@ Copyright (C) Microsoft Corporation. All rights reserved.
 SPDX-License-Identifier: BSD-2-Clause-Patent
 **/
 
+#ifndef CHECK_HW_ERR_REC_HEADER_LIB_H_
+#define CHECK_HW_ERR_REC_HEADER_LIB_H_
+
 /**
  *  Checks that all length and offset fields within the HWErrRec fall within the bounds of
  *  the buffer, all section data is accounted for in their respective section headers, and that
@@ -21,3 +24,5 @@ ValidateCperHeader (
   IN CONST EFI_COMMON_ERROR_RECORD_HEADER  *Err,
   IN CONST UINTN                           Size
   );
+
+#endif