diff --git a/include/semihosting/syscalls.h b/include/semihosting/syscalls.h
index 841a93d..c60ebaf 100644
--- a/include/semihosting/syscalls.h
+++ b/include/semihosting/syscalls.h
@@ -42,4 +42,7 @@
 void semihost_sys_lseek(CPUState *cs, gdb_syscall_complete_cb complete,
                         int fd, int64_t off, int gdb_whence);
 
+void semihost_sys_isatty(CPUState *cs, gdb_syscall_complete_cb complete,
+                         int fd);
+
 #endif /* SEMIHOSTING_SYSCALLS_H */