diff --git a/sfparse.h b/sfparse.h
index 01cc947..26044d0 100644
--- a/sfparse.h
+++ b/sfparse.h
@@ -31,20 +31,20 @@
    libcurl) */
 #if (defined(_WIN32) || defined(__WIN32__)) && !defined(WIN32)
 #  define WIN32
-#endif
+#endif /* (defined(_WIN32) || defined(__WIN32__)) && !defined(WIN32) */
 
 #ifdef __cplusplus
 extern "C" {
-#endif
+#endif /* defined(__cplusplus) */
 
 #if defined(_MSC_VER) && (_MSC_VER < 1800)
 /* MSVC < 2013 does not have inttypes.h because it is not C99
    compliant.  See compiler macros and version number in
    https://sourceforge.net/p/predef/wiki/Compilers/ */
 #  include <stdint.h>
-#else /* !defined(_MSC_VER) || (_MSC_VER >= 1800) */
+#else /* !(defined(_MSC_VER) && (_MSC_VER < 1800)) */
 #  include <inttypes.h>
-#endif /* !defined(_MSC_VER) || (_MSC_VER >= 1800) */
+#endif /* !(defined(_MSC_VER) && (_MSC_VER < 1800)) */
 #include <sys/types.h>
 #include <stddef.h>
 
@@ -423,6 +423,6 @@ void sf_pctdecode(sf_vec *dest, const sf_vec *src);
 
 #ifdef __cplusplus
 }
-#endif
+#endif /* defined(__cplusplus) */
 
-#endif /* SFPARSE_H */
+#endif /* !defined(SFPARSE_H) */
diff --git a/sfparse_test.h b/sfparse_test.h
index 3712d5b..5e47bf6 100644
--- a/sfparse_test.h
+++ b/sfparse_test.h
@@ -54,4 +54,4 @@ munit_void_test_decl(test_sf_parser_key_generated);
 munit_void_test_decl(test_sf_parser_large_generated);
 munit_void_test_decl(test_sf_parser_examples);
 
-#endif /* SFPARSE_TEST_H */
+#endif /* !defined(SFPARSE_TEST_H) */
diff --git a/sfparse_test_main.c b/sfparse_test_main.c
index 742562d..eb3d26d 100644
--- a/sfparse_test_main.c
+++ b/sfparse_test_main.c
@@ -27,7 +27,7 @@
  */
 #ifdef HAVE_CONFIG_H
 #  include <config.h>
-#endif /* HAVE_CONFIG_H */
+#endif /* defined(HAVE_CONFIG_H) */
 
 #include "munit.h"