diff --git a/src/obisig.h b/src/obisig.h
index 4be47db..b01329f 100755
--- a/src/obisig.h
+++ b/src/obisig.h
@@ -25,7 +25,7 @@
  * @author Celine Mercier (celine.mercier@metabarcoding.org)
  *
  */
-bool volatile keep_running;
+extern bool volatile keep_running;
 void sig_handler(int signum);