diff --git a/dataengine.h b/dataengine.h
index f3dc64e8a..804e2d819 100644
--- a/dataengine.h
+++ b/dataengine.h
@@ -271,6 +271,9 @@ class PLASMA_EXPORT DataEngine : public QObject
          * Sets a value for a data source. If the source
          * doesn't exist then it is created.
          *
+         * Note: Passing an empty or invalid QVariant as the value is
+         * functionally equivalent to calling removeSource(source);
+         *
          * @param source the name of the data source
          * @param value the data to associated with the source
          **/
@@ -280,6 +283,9 @@ class PLASMA_EXPORT DataEngine : public QObject
          * Sets a value for a data source. If the source
          * doesn't exist then it is created.
          *
+         * Note: Passing an empty or invalid QVariant as the value is
+         * functionally equivalent to calling removeSource(source);
+         *
          * @param source the name of the data source
          * @param key the key to use for the data
          * @param value the data to associated with the source
@@ -290,6 +296,9 @@ class PLASMA_EXPORT DataEngine : public QObject
          * Adds a set of data to a data source. If the source
          * doesn't exist then it is created.
          *
+         * Note: Passing an empty or invalid QVariant as the value is
+         * functionally equivalent to calling removeSource(source);
+         *
          * @param source the name of the data source
          * @param data the data to add to the source
          **/