diff -up ./clients/memflush.cc.old ./clients/memflush.cc
--- ./clients/memflush.cc.old	2017-02-12 10:12:59.615209225 +0100
+++ ./clients/memflush.cc	2017-02-12 10:13:39.998382783 +0100
@@ -39,7 +39,7 @@ int main(int argc, char *argv[])
 {
   options_parse(argc, argv);
 
-  if (opt_servers == false)
+  if (!opt_servers)
   {
     char *temp;
 
@@ -48,7 +48,7 @@ int main(int argc, char *argv[])
       opt_servers= strdup(temp);
     }
 
-    if (opt_servers == false)
+    if (!opt_servers)
     {
       std::cerr << "No Servers provided" << std::endl;
       exit(EXIT_FAILURE);
diff -up ./clients/memaslap.c.old ./clients/memaslap.c
--- ./clients/memaslap.c.old	2020-02-04 14:11:45.029205068 +0100
+++ ./clients/memaslap.c	2020-02-04 14:12:05.409115227 +0100
@@ -32,6 +32,15 @@
 #include "ms_setting.h"
 #include "ms_thread.h"
 
+/* global structure */
+ms_global_t ms_global;
+
+/* global stats information structure */
+ms_stats_t ms_stats;
+
+/* global statistic structure */
+ms_statistic_t ms_statistic;
+
 #define PROGRAM_NAME    "memslap"
 #define PROGRAM_DESCRIPTION \
                         "Generates workload against memcached servers."
diff -up ./clients/ms_memslap.h.old ./clients/ms_memslap.h
--- ./clients/ms_memslap.h.old	2020-02-04 14:11:50.072182835 +0100
+++ ./clients/ms_memslap.h	2020-02-04 14:12:13.268080586 +0100
@@ -117,13 +117,13 @@ typedef struct global
 } ms_global_t;
 
 /* global structure */
-ms_global_t ms_global;
+extern ms_global_t ms_global;
 
 /* global stats information structure */
-ms_stats_t ms_stats;
+extern ms_stats_t ms_stats;
 
 /* global statistic structure */
-ms_statistic_t ms_statistic;
+extern ms_statistic_t ms_statistic;
 
 #ifdef __cplusplus
 }