diff --git a/clients/cli/devices.c b/clients/cli/devices.c
index d92978f5a6..235690980f 100644
--- a/clients/cli/devices.c
+++ b/clients/cli/devices.c
@@ -2770,7 +2770,7 @@ wifi_list_aps (NMDeviceWifi *wifi,
 	gboolean needs_rescan;
 	WifiListData *data;
 
-	needs_rescan = rescan_cutoff < 0 || (rescan_cutoff > 0 && nm_device_wifi_get_last_scan (wifi) < rescan_cutoff);
+	needs_rescan = rescan_cutoff < 0 || (rescan_cutoff > 0 && nm_device_wifi_get_last_scan (wifi) < (rescan_cutoff * 1000));
 
 	if (needs_rescan) {
 		data = g_slice_new0 (WifiListData);
diff --git a/introspection/org.freedesktop.NetworkManager.Device.Wireless.xml b/introspection/org.freedesktop.NetworkManager.Device.Wireless.xml
index af6e8c7ff3..130385455c 100644
--- a/introspection/org.freedesktop.NetworkManager.Device.Wireless.xml
+++ b/introspection/org.freedesktop.NetworkManager.Device.Wireless.xml
@@ -99,12 +99,12 @@
     <!--
         LastScan:
 
-        The timestamp (in CLOCK_BOOTTIME seconds) for the last finished network scan.
+        The timestamp (in CLOCK_BOOTTIME milliseconds) for the last finished network scan.
         A value of -1 means the device never scanned for access points.
 
         Since: 1.12
     -->
-    <property name="LastScan" type="i" access="read"/>
+    <property name="LastScan" type="x" access="read"/>
 
     <!--
         PropertiesChanged:
diff --git a/libnm/nm-device-wifi.c b/libnm/nm-device-wifi.c
index 851983f46c..1d6e51064c 100644
--- a/libnm/nm-device-wifi.c
+++ b/libnm/nm-device-wifi.c
@@ -59,7 +59,7 @@ typedef struct {
 	NMAccessPoint *active_ap;
 	NMDeviceWifiCapabilities wireless_caps;
 	GPtrArray *aps;
-	gint last_scan;
+	gint64 last_scan;
 
 	RequestScanInfo *scan_info;
 } NMDeviceWifiPrivate;
@@ -273,19 +273,19 @@ nm_device_wifi_get_access_point_by_path (NMDeviceWifi *device,
  * nm_device_wifi_get_last_scan:
  * @device: a #NMDeviceWifi
  *
- * Returns the timestamp (in CLOCK_BOOTTIME seconds) for the last finished
+ * Returns the timestamp (in CLOCK_BOOTTIME milliseconds) for the last finished
  * network scan. A value of -1 means the device never scanned for access points.
  *
  * Returns: the last scan time in seconds
  *
  * Since: 1.12
  **/
-gint
+gint64
 nm_device_wifi_get_last_scan (NMDeviceWifi *device)
 {
-        g_return_val_if_fail (NM_IS_DEVICE_WIFI (device), -1);
+	g_return_val_if_fail (NM_IS_DEVICE_WIFI (device), -1);
 
-        return NM_DEVICE_WIFI_GET_PRIVATE (device)->last_scan;
+	return NM_DEVICE_WIFI_GET_PRIVATE (device)->last_scan;
 }
 
 static GVariant *
@@ -721,7 +721,7 @@ get_property (GObject *object,
 		g_value_take_boxed (value, _nm_utils_copy_object_array (nm_device_wifi_get_access_points (self)));
 		break;
 	case PROP_LAST_SCAN:
-		g_value_set_int (value, nm_device_wifi_get_last_scan (self));
+		g_value_set_int64 (value, nm_device_wifi_get_last_scan (self));
 		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -935,10 +935,10 @@ nm_device_wifi_class_init (NMDeviceWifiClass *wifi_class)
 	 **/
 	g_object_class_install_property
 	        (object_class, PROP_LAST_SCAN,
-	         g_param_spec_int (NM_DEVICE_WIFI_LAST_SCAN, "", "",
-	                           -1, G_MAXINT, -1,
-	                           G_PARAM_READABLE |
-	                           G_PARAM_STATIC_STRINGS));
+	         g_param_spec_int64 (NM_DEVICE_WIFI_LAST_SCAN, "", "",
+	                             -1, G_MAXINT64, -1,
+	                             G_PARAM_READABLE |
+	                             G_PARAM_STATIC_STRINGS));
 
 	/* signals */
 
diff --git a/libnm/nm-device-wifi.h b/libnm/nm-device-wifi.h
index 9885438f02..8448acfea7 100644
--- a/libnm/nm-device-wifi.h
+++ b/libnm/nm-device-wifi.h
@@ -78,8 +78,8 @@ NMAccessPoint *          nm_device_wifi_get_access_point_by_path (NMDeviceWifi *
 
 const GPtrArray *        nm_device_wifi_get_access_points        (NMDeviceWifi *device);
 
-NM_AVAILABLE_IN_1_2
-gint                     nm_device_wifi_get_last_scan            (NMDeviceWifi *device);
+NM_AVAILABLE_IN_1_12
+gint64                   nm_device_wifi_get_last_scan            (NMDeviceWifi *device);
 
 gboolean                 nm_device_wifi_request_scan             (NMDeviceWifi *device,
                                                                   GCancellable *cancellable,
diff --git a/shared/nm-utils/nm-shared-utils.h b/shared/nm-utils/nm-shared-utils.h
index 4b081630cf..588552375e 100644
--- a/shared/nm-utils/nm-shared-utils.h
+++ b/shared/nm-utils/nm-shared-utils.h
@@ -520,8 +520,9 @@ void _nm_utils_strv_sort (const char **strv, gssize len);
 
 /*****************************************************************************/
 
-#define NM_UTILS_NS_PER_SECOND  ((gint64) 1000000000)
-#define NM_UTILS_NS_PER_MSEC    ((gint64) 1000000)
+#define NM_UTILS_NS_PER_SECOND   ((gint64) 1000000000)
+#define NM_UTILS_NS_PER_MSEC     ((gint64) 1000000)
+#define NM_UTILS_MSEC_PER_SECOND ((gint64) 1000)
 #define NM_UTILS_NS_TO_MSEC_CEIL(nsec)      (((nsec) + (NM_UTILS_NS_PER_MSEC - 1)) / NM_UTILS_NS_PER_MSEC)
 
 /*****************************************************************************/
diff --git a/src/devices/wifi/nm-device-iwd.c b/src/devices/wifi/nm-device-iwd.c
index 58bafb81d4..d28fcdbdc7 100644
--- a/src/devices/wifi/nm-device-iwd.c
+++ b/src/devices/wifi/nm-device-iwd.c
@@ -80,7 +80,7 @@ typedef struct {
 	bool            can_connect:1;
 	bool            scanning:1;
 	bool            scan_requested:1;
-	gint32          last_scan;
+	gint64          last_scan;
 } NMDeviceIwdPrivate;
 
 struct _NMDeviceIwd {
@@ -865,7 +865,7 @@ scan_cb (GObject *source, GAsyncResult *res, gpointer user_data)
 
 	priv = NM_DEVICE_IWD_GET_PRIVATE (self);
 	priv->scan_requested = FALSE;
-	priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+	priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 	_notify (self, PROP_LAST_SCAN);
 
 	/* On success, priv->scanning becomes true right before or right
@@ -1535,10 +1535,10 @@ get_property (GObject *object, guint prop_id,
 		g_value_set_boolean (value, priv->scanning);
 		break;
 	case PROP_LAST_SCAN:
-		g_value_set_int (value,
-		                 priv->last_scan > 0
-		                     ? (gint) nm_utils_monotonic_timestamp_as_boottime (priv->last_scan, NM_UTILS_NS_PER_SECOND)
-		                     : -1);
+		g_value_set_int64 (value,
+		                   priv->last_scan > 0
+		                       ? nm_utils_monotonic_timestamp_as_boottime (priv->last_scan, NM_UTILS_NS_PER_MSEC)
+		                       : (gint64) -1);
 		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -1920,9 +1920,9 @@ nm_device_iwd_class_init (NMDeviceIwdClass *klass)
 	                          G_PARAM_STATIC_STRINGS);
 
 	obj_properties[PROP_LAST_SCAN] =
-	    g_param_spec_int (NM_DEVICE_IWD_LAST_SCAN, "", "",
-	                      -1, G_MAXINT, -1,
-	                       G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+	    g_param_spec_int64 (NM_DEVICE_IWD_LAST_SCAN, "", "",
+	                        -1, G_MAXINT64, -1,
+	                         G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
 
 	g_object_class_install_properties (object_class, _PROPERTY_ENUMS_LAST, obj_properties);
 
diff --git a/src/devices/wifi/nm-device-wifi.c b/src/devices/wifi/nm-device-wifi.c
index bcb0e5471f..1a86e13bf6 100644
--- a/src/devices/wifi/nm-device-wifi.c
+++ b/src/devices/wifi/nm-device-wifi.c
@@ -97,8 +97,8 @@ typedef struct {
 	bool              ssid_found:1;
 	bool              is_scanning:1;
 
-	gint32            last_scan;
-	gint32            scheduled_scan_time;
+	gint64            last_scan; /* milliseconds */
+	gint32            scheduled_scan_time; /* seconds */
 	guint8            scan_interval; /* seconds */
 	guint             pending_scan_id;
 	guint             ap_dump_id;
@@ -1127,7 +1127,7 @@ _nm_device_wifi_request_scan (NMDeviceWifi *self,
 {
 	NMDeviceWifiPrivate *priv = NM_DEVICE_WIFI_GET_PRIVATE (self);
 	NMDevice *device = NM_DEVICE (self);
-	gint32 last_scan;
+	gint64 last_scan;
 
 	if (   !priv->enabled
 	    || !priv->sup_iface
@@ -1148,8 +1148,8 @@ _nm_device_wifi_request_scan (NMDeviceWifi *self,
 		return;
 	}
 
-	last_scan = nm_supplicant_interface_get_last_scan_time (priv->sup_iface);
-	if (last_scan && (nm_utils_get_monotonic_timestamp_s () - last_scan) < 10) {
+	last_scan = nm_supplicant_interface_get_last_scan (priv->sup_iface);
+	if (last_scan && (nm_utils_get_monotonic_timestamp_ms () - last_scan) < 10 * NM_UTILS_MSEC_PER_SECOND) {
 		g_dbus_method_invocation_return_error_literal (invocation,
 		                                               NM_DEVICE_ERROR,
 		                                               NM_DEVICE_ERROR_NOT_ALLOWED,
@@ -1423,7 +1423,7 @@ supplicant_iface_scan_done_cb (NMSupplicantInterface *iface,
 
 	_LOGD (LOGD_WIFI, "wifi-scan: scan-done callback: %s", success ? "successful" : "failed");
 
-	priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+	priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 	_notify (self, PROP_LAST_SCAN);
 	schedule_scan (self, success);
 
@@ -1447,9 +1447,9 @@ ap_list_dump (gpointer user_data)
 		NMWifiAP *ap;
 		gint32 now_s = nm_utils_get_monotonic_timestamp_s ();
 
-		_LOGD (LOGD_WIFI_SCAN, "APs: [now:%u last:%u next:%u]",
+		_LOGD (LOGD_WIFI_SCAN, "APs: [now:%u last:%" G_GINT64_FORMAT " next:%u]",
 		       now_s,
-		       priv->last_scan,
+		       priv->last_scan / NM_UTILS_MSEC_PER_SECOND,
 		       priv->scheduled_scan_time);
 		c_list_for_each_entry (ap, &priv->aps_lst_head, aps_lst)
 			_ap_dump (self, LOGL_DEBUG, ap, "dump", now_s);
@@ -3185,10 +3185,10 @@ get_property (GObject *object, guint prop_id,
 		g_value_set_boolean (value, priv->is_scanning);
 		break;
 	case PROP_LAST_SCAN:
-		g_value_set_int (value,
-		                 priv->last_scan > 0
-		                     ? (gint) nm_utils_monotonic_timestamp_as_boottime (priv->last_scan, NM_UTILS_NS_PER_SECOND)
-		                     : -1);
+		g_value_set_int64 (value,
+		                   priv->last_scan > 0
+		                       ? nm_utils_monotonic_timestamp_as_boottime (priv->last_scan, NM_UTILS_NS_PER_MSEC)
+		                       : (gint64) -1);
 		break;
 	default:
 		G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -3369,9 +3369,9 @@ nm_device_wifi_class_init (NMDeviceWifiClass *klass)
 	                          G_PARAM_STATIC_STRINGS);
 
 	obj_properties[PROP_LAST_SCAN] =
-	    g_param_spec_int (NM_DEVICE_WIFI_LAST_SCAN, "", "",
-	                      -1, G_MAXINT, -1,
-	                       G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
+	    g_param_spec_int64 (NM_DEVICE_WIFI_LAST_SCAN, "", "",
+	                        -1, G_MAXINT64, -1,
+	                         G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
 
 	g_object_class_install_properties (object_class, _PROPERTY_ENUMS_LAST, obj_properties);
 
diff --git a/src/devices/wifi/nm-wifi-common.c b/src/devices/wifi/nm-wifi-common.c
index 0030b32dff..8e079d1151 100644
--- a/src/devices/wifi/nm-wifi-common.c
+++ b/src/devices/wifi/nm-wifi-common.c
@@ -200,7 +200,7 @@ const NMDBusInterfaceInfoExtended nm_interface_info_device_wireless = {
 			NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_L ("AccessPoints",         "ao", NM_DEVICE_WIFI_ACCESS_POINTS),
 			NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_L ("ActiveAccessPoint",    "o",  NM_DEVICE_WIFI_ACTIVE_ACCESS_POINT),
 			NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE_L ("WirelessCapabilities", "u",  NM_DEVICE_WIFI_CAPABILITIES),
-			NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE   ("LastScan",             "i",  NM_DEVICE_WIFI_LAST_SCAN),
+			NM_DEFINE_DBUS_PROPERTY_INFO_EXTENDED_READABLE   ("LastScan",             "x",  NM_DEVICE_WIFI_LAST_SCAN),
 		),
 	),
 	.legacy_property_changed = TRUE,
diff --git a/src/supplicant/nm-supplicant-interface.c b/src/supplicant/nm-supplicant-interface.c
index 3511b151e4..71e6a35ac5 100644
--- a/src/supplicant/nm-supplicant-interface.c
+++ b/src/supplicant/nm-supplicant-interface.c
@@ -129,7 +129,7 @@ typedef struct {
 	GHashTable *   bss_proxies;
 	char *         current_bss;
 
-	gint32         last_scan; /* timestamp as returned by nm_utils_get_monotonic_timestamp_s() */
+	gint64         last_scan; /* timestamp as returned by nm_utils_get_monotonic_timestamp_ms() */
 
 } NMSupplicantInterfacePrivate;
 
@@ -209,7 +209,7 @@ bss_proxy_properties_changed_cb (GDBusProxy *proxy,
 	NMSupplicantInterfacePrivate *priv = NM_SUPPLICANT_INTERFACE_GET_PRIVATE (self);
 
 	if (priv->scanning)
-		priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+		priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 
 	g_signal_emit (self, signals[BSS_UPDATED], 0,
 	               g_dbus_proxy_get_object_path (proxy),
@@ -344,7 +344,7 @@ set_state (NMSupplicantInterface *self, NMSupplicantInterfaceState new_state)
 
 	if (   priv->state == NM_SUPPLICANT_INTERFACE_STATE_SCANNING
 	    || old_state == NM_SUPPLICANT_INTERFACE_STATE_SCANNING)
-		priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+		priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 
 	/* Disconnect reason is no longer relevant when not in the DISCONNECTED state */
 	if (priv->state != NM_SUPPLICANT_INTERFACE_STATE_DISCONNECTED)
@@ -406,7 +406,7 @@ set_scanning (NMSupplicantInterface *self, gboolean new_scanning)
 
 		/* Cache time of last scan completion */
 		if (priv->scanning == FALSE)
-			priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+			priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 
 		_notify (self, PROP_SCANNING);
 	}
@@ -438,8 +438,8 @@ nm_supplicant_interface_get_current_bss (NMSupplicantInterface *self)
 	return priv->state >= NM_SUPPLICANT_INTERFACE_STATE_READY ? priv->current_bss : NULL;
 }
 
-gint32
-nm_supplicant_interface_get_last_scan_time (NMSupplicantInterface *self)
+gint64
+nm_supplicant_interface_get_last_scan (NMSupplicantInterface *self)
 {
 	return NM_SUPPLICANT_INTERFACE_GET_PRIVATE (self)->last_scan;
 }
@@ -987,7 +987,7 @@ wpas_iface_scan_done (GDBusProxy *proxy,
 	NMSupplicantInterfacePrivate *priv = NM_SUPPLICANT_INTERFACE_GET_PRIVATE (self);
 
 	/* Cache last scan completed time */
-	priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+	priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 	priv->scan_done_success |= success;
 	scan_done_emit_signal (self);
 }
@@ -1002,7 +1002,7 @@ wpas_iface_bss_added (GDBusProxy *proxy,
 	NMSupplicantInterfacePrivate *priv = NM_SUPPLICANT_INTERFACE_GET_PRIVATE (self);
 
 	if (priv->scanning)
-		priv->last_scan = nm_utils_get_monotonic_timestamp_s ();
+		priv->last_scan = nm_utils_get_monotonic_timestamp_ms ();
 
 	bss_add_new (self, path);
 }
diff --git a/src/supplicant/nm-supplicant-interface.h b/src/supplicant/nm-supplicant-interface.h
index f32ad8dda2..31272b3c11 100644
--- a/src/supplicant/nm-supplicant-interface.h
+++ b/src/supplicant/nm-supplicant-interface.h
@@ -110,7 +110,7 @@ gboolean nm_supplicant_interface_get_scanning (NMSupplicantInterface *self);
 
 const char *nm_supplicant_interface_get_current_bss (NMSupplicantInterface *self);
 
-gint32 nm_supplicant_interface_get_last_scan_time (NMSupplicantInterface *self);
+gint64 nm_supplicant_interface_get_last_scan (NMSupplicantInterface *self);
 
 const char *nm_supplicant_interface_get_ifname (NMSupplicantInterface *self);
 
diff --git a/tools/test-networkmanager-service.py b/tools/test-networkmanager-service.py
index e866e0a617..65f168cb21 100755
--- a/tools/test-networkmanager-service.py
+++ b/tools/test-networkmanager-service.py
@@ -924,7 +924,7 @@ class WifiDevice(Device):
             PRP_WIFI_WIRELESS_CAPABILITIES: dbus.UInt32(0xFF),
             PRP_WIFI_ACCESS_POINTS:         ExportedObj.to_path_array(self.aps),
             PRP_WIFI_ACTIVE_ACCESS_POINT:   ExportedObj.to_path(None),
-            PRP_WIFI_LAST_SCAN:             dbus.Int32(0x70000000),
+            PRP_WIFI_LAST_SCAN:             dbus.Int64(0x7000000000000000),
         }
 
         self.dbus_interface_add(IFACE_WIFI, props, WifiDevice.PropertiesChanged)