diff --git a/include/wx/platform.h b/include/wx/platform.h
index 47c1c4778c..91749a1c8b 100644
--- a/include/wx/platform.h
+++ b/include/wx/platform.h
@@ -280,6 +280,11 @@
 #    if defined(__INNOTEK_LIBC__)
         /* Ensure visibility of strnlen declaration */
 #        define _GNU_SOURCE
+#    endif
+
+#    if defined(__CYGWIN__)
+        /* Ensure visibility of Dl_info and pthread_setconcurrency declarations */
+#        define _GNU_SOURCE
 #    endif
 
     /* define __HPUX__ for HP-UX where standard macro is __hpux */