--- /dev/null
+--- a/src/bmx.h
++++ b/src/bmx.h
+@@ -290,7 +290,7 @@ enum ADGSN {
+ #define SUCCESS 0
+ #define FAILURE -1
+
+-const void* FAILURE_PTR;
++extern const void* FAILURE_PTR;
+
+
+ #define MAX_SELECT_TIMEOUT_MS 1100 /* MUST be smaller than (1000/2) to fit into max tv_usec */