diff --git a/include/transport/memoryusage.h b/include/transport/memoryusage.h
index d2080e218ce2d662378d396cc18b998669412b83..d38917d96638ffde8d30217eb68ef37bc4706fa0 100644
--- a/include/transport/memoryusage.h
+++ b/include/transport/memoryusage.h
@@ -22,10 +22,14 @@
 
 #include <vector>
 
+#ifndef WIN32
+#include "signal.h"
+#endif
+
 namespace Transport {
 
 #ifndef WIN32
-	void process_mem_usage(double& shared, double& resident_set);
+	void process_mem_usage(double& shared, double& resident_set, pid_t pid = 0);
 #endif
 
 }
\ No newline at end of file