diff --git a/client/client_state.C b/client/client_state.C
index 241e92a441..5b1a45d630 100644
--- a/client/client_state.C
+++ b/client/client_state.C
@@ -328,7 +328,9 @@ int CLIENT_STATE::net_sleep(double x) {
 bool CLIENT_STATE::do_something() {
     int actions = 0, reason, retval;
     SCOPE_MSG_LOG scope_messages(log_messages, CLIENT_MSG_LOG::DEBUG_POLL);
-
+#ifndef _WIN32
+    check_idle();
+#endif
     check_suspend_activities(reason);
     if (reason) {
         if (!activities_suspended) {
diff --git a/client/client_state.h b/client/client_state.h
index d5e30e2730..31bace7b6b 100644
--- a/client/client_state.h
+++ b/client/client_state.h
@@ -230,6 +230,9 @@ private:
     int resume_network();
     void install_global_prefs();
     void show_global_prefs_source(bool);
+#ifndef _WIN32
+    void check_idle();
+#endif
 
 // --------------- cs_scheduler.C:
 public:
diff --git a/client/cs_prefs.C b/client/cs_prefs.C
index 2753197eb4..6b111ddc56 100644
--- a/client/cs_prefs.C
+++ b/client/cs_prefs.C
@@ -25,6 +25,15 @@
 #include "stdafx.h"
 #endif
 
+#ifndef _WIN32
+#if HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#if HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#endif
+
 #include "util.h"
 #include "filesys.h"
 #include "file_names.h"
@@ -92,6 +101,22 @@ inline bool now_between_two_hours(int start_hour, int end_hour) {
     }
 }
 
+#ifndef _WIN32
+// returns true iff device was last accessed before t
+// or if an error occurred looking at the device.
+inline bool device_idle(time_t t, char *device) {
+    struct stat sbuf;
+    return stat(device, &sbuf) || (sbuf.st_atime < t);
+}
+
+void CLIENT_STATE::check_idle() {
+    time_t idle_time =
+        time(NULL) - (long) (60 * global_prefs.idle_time_to_run);
+    user_idle = device_idle(idle_time, "/dev/kbd")
+        && device_idle(idle_time, "/dev/mouse");
+}
+#endif
+
 // See if (on the basis of user run request and prefs)
 // we should suspend activities.
 //