diff --git a/include/hamlib/rig.h b/include/hamlib/rig.h
index 1a1f81b47..a4e18e104 100644
--- a/include/hamlib/rig.h
+++ b/include/hamlib/rig.h
@@ -57,6 +57,25 @@
 #  define __END_DECLS        /* empty */
 #endif
 
+#ifndef thread_local
+# if __STDC_VERSION__ >= 201112 && !defined __STDC_NO_THREADS__
+#  define thread_local _Thread_local
+# elif defined _WIN32 && ( \
+       defined _MSC_VER || \
+       defined __ICL || \
+       defined __DMC__ || \
+       defined __BORLANDC__ )
+#  define thread_local __declspec(thread) 
+/* note that ICC (linux) and Clang are covered by __GNUC__ */
+# elif defined __GNUC__ || \
+       defined __SUNPRO_C || \
+       defined __xlC__
+#  define thread_local __thread
+# else
+#  error "Cannot define thread_local"
+# endif
+#endif
+
 /* HAMLIB_PARAMS is a macro used to wrap function prototypes, so that compilers
  * that don't understand ANSI C prototypes still work, and ANSI C
  * compilers can issue warnings about type mismatches. */
@@ -1732,7 +1751,7 @@ struct rig_state {
     rmode_t current_mode;       /*!< Mode currently set */
     pbwidth_t current_width;    /*!< Passband width currently set */
     vfo_t tx_vfo;               /*!< Tx VFO currently set */
-    int mode_list;              /*!< Complete list of modes for this rig */
+    rmode_t mode_list;              /*!< Complete list of modes for this rig */
     int transmit;               /*!< rig should be transmitting i.e. hard
                                      wired PTT asserted - used by rigs that
                                      don't do CAT while in Tx */