diff --git a/src/include/c.h b/src/include/c.h
index 6558801e5ff..831c89f473d 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -836,37 +836,43 @@ extern void ExceptionalCondition(const char *conditionName,
  * The macro StaticAssertDecl() is suitable for use at file scope (outside of
  * any function).
  *
- * On recent C++ compilers, we can use standard static_assert().
- *
  * Otherwise we fall back on a kluge that assumes the compiler will complain
  * about a negative width for a struct bit-field.  This will not include a
  * helpful error message, but it beats not getting an error at all.
  */
-#if !defined(__cplusplus) && defined(HAVE__STATIC_ASSERT)
-/* Default C implementation */
+#ifndef __cplusplus
+#ifdef HAVE__STATIC_ASSERT
 #define StaticAssertStmt(condition, errmessage) \
 	do { _Static_assert(condition, errmessage); } while(0)
 #define StaticAssertExpr(condition, errmessage) \
 	((void) ({ StaticAssertStmt(condition, errmessage); true; }))
 #define StaticAssertDecl(condition, errmessage) \
 	_Static_assert(condition, errmessage)
-#elif defined(__cplusplus) && __cpp_static_assert >= 200410
-/* Default C++ implementation */
-#define StaticAssertStmt(condition, errmessage) \
-	static_assert(condition, errmessage)
-#define StaticAssertExpr(condition, errmessage) \
-	({ static_assert(condition, errmessage); })
-#define StaticAssertDecl(condition, errmessage) \
-	static_assert(condition, errmessage)
-#else
-/* Fallback implementation for C and C++ */
+#else							/* !HAVE__STATIC_ASSERT */
 #define StaticAssertStmt(condition, errmessage) \
 	((void) sizeof(struct { int static_assert_failure : (condition) ? 1 : -1; }))
 #define StaticAssertExpr(condition, errmessage) \
 	StaticAssertStmt(condition, errmessage)
 #define StaticAssertDecl(condition, errmessage) \
 	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
-#endif
+#endif							/* HAVE__STATIC_ASSERT */
+#else							/* C++ */
+#if defined(__cpp_static_assert) && __cpp_static_assert >= 200410
+#define StaticAssertStmt(condition, errmessage) \
+	static_assert(condition, errmessage)
+#define StaticAssertExpr(condition, errmessage) \
+	({ static_assert(condition, errmessage); })
+#define StaticAssertDecl(condition, errmessage) \
+	static_assert(condition, errmessage)
+#else							/* !__cpp_static_assert */
+#define StaticAssertStmt(condition, errmessage) \
+	do { struct static_assert_struct { int static_assert_failure : (condition) ? 1 : -1; }; } while(0)
+#define StaticAssertExpr(condition, errmessage) \
+	((void) ({ StaticAssertStmt(condition, errmessage); }))
+#define StaticAssertDecl(condition, errmessage) \
+	extern void static_assert_func(int static_assert_failure[(condition) ? 1 : -1])
+#endif							/* __cpp_static_assert */
+#endif							/* C++ */
 
 
 /*