diff --git a/test_apps/esme.c b/test_apps/esme.c
index 77fb198..5d9dafd 100644
--- a/test_apps/esme.c
+++ b/test_apps/esme.c
@@ -23,6 +23,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <libxml/xmlmemory.h>
diff --git a/test_apps/sendwp.c b/test_apps/sendwp.c
index b719c45..f75af76 100644
--- a/test_apps/sendwp.c
+++ b/test_apps/sendwp.c
@@ -23,6 +23,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <libxml/xmlmemory.h>
diff --git a/test_apps/smpp.c b/test_apps/smpp.c
index c764907..2cdb138 100644
--- a/test_apps/smpp.c
+++ b/test_apps/smpp.c
@@ -23,6 +23,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <sys/types.h>
diff --git a/test_apps/tcp.c b/test_apps/tcp.c
index 4cf681d..3051df2 100644
--- a/test_apps/tcp.c
+++ b/test_apps/tcp.c
@@ -28,6 +28,7 @@
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 #include <libxml/xmlmemory.h>