diff --git a/slideshow/source/engine/activities/accumulation.hxx b/slideshow/source/engine/activities/accumulation.hxx
index ec04195597af..66e0cdedd930 100644
--- a/slideshow/source/engine/activities/accumulation.hxx
+++ b/slideshow/source/engine/activities/accumulation.hxx
@@ -17,8 +17,7 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-#ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACCUMULATION_HXX
-#define INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACCUMULATION_HXX
+#pragma once
 
 #include <sal/types.h>
 #include <rtl/ustring.hxx>
@@ -79,6 +78,4 @@ namespace slideshow::internal
 
 }
 
-#endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACCUMULATION_HXX
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/slideshow/source/engine/activities/activitybase.hxx b/slideshow/source/engine/activities/activitybase.hxx
index e76c84d8e6c5..c341ad5cfbe0 100644
--- a/slideshow/source/engine/activities/activitybase.hxx
+++ b/slideshow/source/engine/activities/activitybase.hxx
@@ -17,8 +17,7 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-#ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYBASE_HXX
-#define INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYBASE_HXX
+#pragma once
 
 #include <animationactivity.hxx>
 #include "activityparameters.hxx"
@@ -138,6 +137,4 @@ private:
 
 } // namespace presentation::internal
 
-#endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYBASE_HXX
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/slideshow/source/engine/activities/activityparameters.hxx b/slideshow/source/engine/activities/activityparameters.hxx
index 9df762838530..01eeebe6c91c 100644
--- a/slideshow/source/engine/activities/activityparameters.hxx
+++ b/slideshow/source/engine/activities/activityparameters.hxx
@@ -17,8 +17,7 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-#ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYPARAMETERS_HXX
-#define INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYPARAMETERS_HXX
+#pragma once
 
 #include <event.hxx>
 #include <eventqueue.hxx>
@@ -129,6 +128,4 @@ struct ActivityParameters
 
 } // namespace presentation::internal
 
-#endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_ACTIVITYPARAMETERS_HXX
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/slideshow/source/engine/activities/continuousactivitybase.hxx b/slideshow/source/engine/activities/continuousactivitybase.hxx
index 8fd19d421e0c..c6421ea9d461 100644
--- a/slideshow/source/engine/activities/continuousactivitybase.hxx
+++ b/slideshow/source/engine/activities/continuousactivitybase.hxx
@@ -17,8 +17,7 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-#ifndef INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_CONTINUOUSACTIVITYBASE_HXX
-#define INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_CONTINUOUSACTIVITYBASE_HXX
+#pragma once
 
 #include "simplecontinuousactivitybase.hxx"
 
@@ -60,6 +59,4 @@ namespace slideshow::internal
 
 }
 
-#endif // INCLUDED_SLIDESHOW_SOURCE_ENGINE_ACTIVITIES_CONTINUOUSACTIVITYBASE_HXX
-
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */