diff --git a/src/tools/fs_shell/sem.cpp b/src/tools/fs_shell/sem.cpp
index 8d3d8e775d..b5193b281b 100644
--- a/src/tools/fs_shell/sem.cpp
+++ b/src/tools/fs_shell/sem.cpp
@@ -5,6 +5,8 @@
 
 #include "compatibility.h"
 
+#include <string.h>
+
 #include <OS.h>
 
 #include "fssh_errors.h"