diff --git a/c++/src/H5AbstractDs.h b/c++/src/H5AbstractDs.h
index fe6e033c3af..b84867b2cb9 100644
--- a/c++/src/H5AbstractDs.h
+++ b/c++/src/H5AbstractDs.h
@@ -12,8 +12,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef __AbstractDs_H
-#define __AbstractDs_H
+#ifndef H5AbstractDs_H
+#define H5AbstractDs_H
 
 namespace H5 {
 
@@ -81,4 +81,4 @@ class H5_DLLCPP AbstractDs {
 }; // end of AbstractDs
 } // namespace H5
 
-#endif // __AbstractDs_H
+#endif // H5AbstractDs_H
diff --git a/c++/src/H5CommonFG.h b/c++/src/H5CommonFG.h
index 2e5ccf3b4d5..d87f9ca1348 100644
--- a/c++/src/H5CommonFG.h
+++ b/c++/src/H5CommonFG.h
@@ -12,8 +12,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef __CommonFG_H
-#define __CommonFG_H
+#ifndef H5CommonFG_H
+#define H5CommonFG_H
 
 namespace H5 {
 
@@ -83,7 +83,7 @@ class H5_DLLCPP CommonFG {
 }; // end of CommonFG
 } // namespace H5
 
-#endif // __CommonFG_H
+#endif // H5CommonFG_H
 
 /***************************************************************************
                                 Design Note
diff --git a/c++/src/H5Group.h b/c++/src/H5Group.h
index ae5bb4aec3d..6e82e21473a 100644
--- a/c++/src/H5Group.h
+++ b/c++/src/H5Group.h
@@ -12,8 +12,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef __Group_H
-#define __Group_H
+#ifndef H5Group_H
+#define H5Group_H
 
 namespace H5 {
 
@@ -83,4 +83,4 @@ class H5_DLLCPP Group : public H5Object, public CommonFG {
 }; // end of Group
 } // namespace H5
 
-#endif // __Group_H
+#endif // H5Group_H
diff --git a/c++/src/H5IdComponent.h b/c++/src/H5IdComponent.h
index b756a3d087e..383d42d333f 100644
--- a/c++/src/H5IdComponent.h
+++ b/c++/src/H5IdComponent.h
@@ -12,8 +12,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef __IdComponent_H
-#define __IdComponent_H
+#ifndef H5IdComponent_H
+#define H5IdComponent_H
 
 namespace H5 {
 
@@ -113,4 +113,4 @@ class H5_DLLCPP IdComponent {
 }; // end class IdComponent
 } // namespace H5
 
-#endif // __IdComponent_H
+#endif // H5IdComponent_H
diff --git a/hl/src/hdf5_hl.h b/hl/src/hdf5_hl.h
index 580c09a839d..ba6aa09ccfc 100644
--- a/hl/src/hdf5_hl.h
+++ b/hl/src/hdf5_hl.h
@@ -17,8 +17,8 @@
  * fill this file with lots of gunk...
  */
 
-#ifndef _HDF5_HL_H
-#define _HDF5_HL_H
+#ifndef HDF5_HL_H
+#define HDF5_HL_H
 #include "hdf5.h"       /* hdf5 main library */
 #include "H5DOpublic.h" /* dataset optimization */
 #include "H5DSpublic.h" /* dimension scales */
@@ -28,4 +28,4 @@
 #include "H5PTpublic.h" /* packet table */
 #include "H5LDpublic.h" /* lite dataset */
 
-#endif /*H5_INCLUDE_HL*/
+#endif /*HDF5_HL_H*/
diff --git a/test/cache_common.h b/test/cache_common.h
index bc9f33bace4..126a8b375cf 100644
--- a/test/cache_common.h
+++ b/test/cache_common.h
@@ -17,8 +17,8 @@
  *        This file contains common #defines, type definitions, and
  *        externs for tests of the cache implemented in H5C.c
  */
-#ifndef _CACHE_COMMON_H
-#define _CACHE_COMMON_H
+#ifndef CACHE_COMMON_H
+#define CACHE_COMMON_H
 
 #define H5C_FRIEND /*suppress error about including H5Cpkg   */
 #define H5F_FRIEND /*suppress error about including H5Fpkg      */
@@ -694,4 +694,4 @@ H5TEST_DLL void dump_LRU(H5F_t * file_ptr);
 }
 #endif
 
-#endif /* _CACHE_COMMON_H */
+#endif /* CACHE_COMMON_H */
diff --git a/test/external_common.h b/test/external_common.h
index d338a704d1b..6215be9b70e 100644
--- a/test/external_common.h
+++ b/test/external_common.h
@@ -17,8 +17,8 @@
  *
  * Purpose:     Private function for external.c and external_env.c
  */
-#ifndef _EXTERNAL_COMMON_H
-#define _EXTERNAL_COMMON_H
+#ifndef EXTERNAL_COMMON_H
+#define EXTERNAL_COMMON_H
 
 /* Include test header files */
 #include "h5test.h"
@@ -41,4 +41,4 @@ H5TEST_DLL herr_t reset_raw_data_files(hbool_t is_env);
 }
 #endif
 
-#endif /* _EXTERNAL_COMMON_H */
+#endif /* EXTERNAL_COMMON_H */
diff --git a/test/external_fname.h b/test/external_fname.h
index 25455473b6e..c2cd059837c 100644
--- a/test/external_fname.h
+++ b/test/external_fname.h
@@ -17,8 +17,8 @@
  *
  * Purpose:     Private declaration for external.c and external_env.c
  */
-#ifndef _EXTERNAL_FNAME_H
-#define _EXTERNAL_FNAME_H
+#ifndef EXTERNAL_FNAME_H
+#define EXTERNAL_FNAME_H
 
 /* Include test header files */
 #include "h5test.h"
@@ -26,4 +26,4 @@
 static const char *EXT_FNAME[] = {"extern_1",          "extern_2", "extern_3", "extern_4",
                                   "extern_dir/file_1", "extern_5", NULL};
 
-#endif /* _EXTERNAL_FNAME_H */
+#endif /* EXTERNAL_FNAME_H */
diff --git a/test/swmr_common.h b/test/swmr_common.h
index e342580d016..d0d829d3589 100644
--- a/test/swmr_common.h
+++ b/test/swmr_common.h
@@ -11,8 +11,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef _SWMR_COMMON_H
-#define _SWMR_COMMON_H
+#ifndef SWMR_COMMON_H
+#define SWMR_COMMON_H
 
 /***********/
 /* Headers */
@@ -75,4 +75,4 @@ H5TEST_DLL int            print_metadata_retries_info(hid_t fid);
 }
 #endif
 
-#endif /* _SWMR_COMMON_H */
+#endif /* SWMR_COMMON_H */
diff --git a/tools/lib/ph5diff.h b/tools/lib/ph5diff.h
index 8e884dd4c9f..7dce495a93c 100644
--- a/tools/lib/ph5diff.h
+++ b/tools/lib/ph5diff.h
@@ -11,8 +11,8 @@
  * help@hdfgroup.org.                                                        *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
 
-#ifndef _PH5DIFF_H__
-#define _PH5DIFF_H__
+#ifndef PH5DIFF_H
+#define PH5DIFF_H
 
 /* Send from manager to workers */
 #define MPI_TAG_ARGS      1
@@ -40,4 +40,4 @@ struct diffs_found {
     int     not_cmp;
 };
 
-#endif /* _PH5DIFF_H__ */
+#endif /* PH5DIFF_H */