diff --git a/ossig.h b/ossig.h
index 8764c167..35e8f789 100644
--- a/ossig.h
+++ b/ossig.h
@@ -82,12 +82,16 @@ struct SignalHandler
             // Don't step on another's handler if Overwrite=false
             if (m_old.sa_handler != 0 && !O) break;
 
-            // Sun Studio 12.2-12.4 needs the two casts, and they must be C-style casts
-            new_handler.sa_handler = (pfn ? pfn : &NullSignalHandler);
-            new_handler.sa_flags = (pfn ? flags : 0);
-
+#if defined __CYGWIN__
+            // http://github.com/weidai11/cryptopp/issues/315
+            memset(&new_handler, 0x00, sizeof(new_handler));
+#else
             ret = sigemptyset (&new_handler.sa_mask);
             if (ret != 0) break; // Failed
+#endif
+
+            new_handler.sa_handler = (pfn ? pfn : &NullSignalHandler);
+            new_handler.sa_flags = (pfn ? flags : 0);
 
             // Install it
             ret = sigaction (S, &new_handler, 0);