Fix compiler warning
diff --git a/common/main.c b/common/main.c
index 2922624..1389958 100644
--- a/common/main.c
+++ b/common/main.c
@@ -26,6 +26,9 @@
 #include <common.h>
 #include <watchdog.h>
 #include <command.h>
+#ifdef CONFIG_MODEM_SUPPORT
+#include <malloc.h>		/* for free() prototype */
+#endif
 
 #ifdef CFG_HUSH_PARSER
 #include <hush.h>