event: Constify operations
diff --git a/src/sdeventplus/event.cpp b/src/sdeventplus/event.cpp
index e8e8d19..1d31f91 100644
--- a/src/sdeventplus/event.cpp
+++ b/src/sdeventplus/event.cpp
@@ -44,7 +44,7 @@
     return Event(event, std::false_type(), sdevent);
 }
 
-int Event::loop()
+int Event::loop() const
 {
     int r = sdevent->sd_event_loop(event.get());
     if (r < 0)
@@ -54,7 +54,7 @@
     return r;
 }
 
-int Event::get_watchdog()
+int Event::get_watchdog() const
 {
     int r = sdevent->sd_event_get_watchdog(event.get());
     if (r < 0)
@@ -64,7 +64,7 @@
     return r;
 }
 
-int Event::set_watchdog(int b)
+int Event::set_watchdog(int b) const
 {
     int r = sdevent->sd_event_set_watchdog(event.get(), b);
     if (r < 0)
diff --git a/src/sdeventplus/event.hpp b/src/sdeventplus/event.hpp
index e7c007f..a583dfb 100644
--- a/src/sdeventplus/event.hpp
+++ b/src/sdeventplus/event.hpp
@@ -20,9 +20,9 @@
     static Event
         get_default(const internal::SdEvent* sdevent = &internal::sdevent_impl);
 
-    int loop();
-    int get_watchdog();
-    int set_watchdog(int b);
+    int loop() const;
+    int get_watchdog() const;
+    int set_watchdog(int b) const;
 
   private:
     const internal::SdEvent* sdevent;