diff --git a/lib/isc/include/isc/util.h b/lib/isc/include/isc/util.h
index 2d99015034..64c26587ac 100644
--- a/lib/isc/include/isc/util.h
+++ b/lib/isc/include/isc/util.h
@@ -54,8 +54,6 @@
 #elif WIN32
 #define ISC_CONSTRUCTOR(priority)
 #define ISC_DESTRUCTOR(priority)
-#else
-#error Either __attribute__((constructor|destructor))__ or DllMain support needed to compile BIND 9.
 #endif
 
 /*%
diff --git a/lib/isc/lib.c b/lib/isc/lib.c
index b1afa2b355..31724218ff 100644
--- a/lib/isc/lib.c
+++ b/lib/isc/lib.c
@@ -17,10 +17,15 @@
 #include <isc/tls.h>
 #include <isc/util.h>
 
+#include "config.h"
 #include "mem_p.h"
 #include "tls_p.h"
 #include "trampoline_p.h"
 
+#ifndef ISC_CONSTRUCTOR
+#error Either __attribute__((constructor|destructor))__ or DllMain support needed to compile BIND 9.
+#endif
+
 /***
  *** Functions
  ***/