--- src/shared/musl_missing.h
+++ src/shared/musl_missing.h
@@ -41,9 +41,10 @@ extern char *program_invocation_short_name;
  * + test if the effective capability bit was set on the executable file
  * + test if the process has a nonempty permitted capability set
  */
-#if !defined(HAVE_SECURE_GETENV) && !defined(HAVE___SECURE_GETENV)
+#if ! HAVE_SECURE_GETENV && ! HAVE___SECURE_GETENV
 #  define secure_getenv(name) \
         (issetugid() ? NULL : getenv(name))
+#  undef HAVE_SECURE_GETENV
 #  define HAVE_SECURE_GETENV 1
 #endif // HAVE_[__]SECURE_GETENV