diff --git a/src/analysis/interpolation/qgsinterpolator.h b/src/analysis/interpolation/qgsinterpolator.h
index cd1dad17caae..538e1bf63dd7 100644
--- a/src/analysis/interpolation/qgsinterpolator.h
+++ b/src/analysis/interpolation/qgsinterpolator.h
@@ -110,9 +110,10 @@ class ANALYSIS_EXPORT QgsInterpolator
      * Calculates interpolation value for map coordinates x, y
      * \param x x-coordinate (in map units)
      * \param y y-coordinate (in map units)
-     * \param result out: interpolation result
+     * \param result interpolation result
      * \param feedback optional feedback object for progress and cancelation support
-     * \returns 0 in case of success*/
+     * \returns 0 in case of success
+     */
     virtual int interpolatePoint( double x, double y, double &result SIP_OUT, QgsFeedback *feedback = nullptr ) = 0;
 
     //! \note not available in Python bindings
diff --git a/src/core/geometry/qgsgeometry.h b/src/core/geometry/qgsgeometry.h
index 66925477ff99..0ab270ca2951 100644
--- a/src/core/geometry/qgsgeometry.h
+++ b/src/core/geometry/qgsgeometry.h
@@ -876,6 +876,7 @@ class CORE_EXPORT QgsGeometry
      * \param center Center of the minimal enclosing circle returneds
      * \param radius Radius of the minimal enclosing circle returned
      * \param segments Number of segments used to segment geometry. \see QgsEllipse::toPolygon()
+     * \returns the minimal enclosing circle as a QGIS geometry
      * \since QGIS 3.0
      */
     QgsGeometry minimalEnclosingCircle( QgsPointXY &center SIP_OUT, double &radius SIP_OUT, unsigned int segments = 36 ) const;
diff --git a/src/core/qgsunittypes.h b/src/core/qgsunittypes.h
index b682f4bdc7e6..4c13c55c57b6 100644
--- a/src/core/qgsunittypes.h
+++ b/src/core/qgsunittypes.h
@@ -226,6 +226,7 @@ class CORE_EXPORT QgsUnitTypes
      * Converts a translated string to a distance unit.
      * \param string string representing a distance unit
      * \param ok optional boolean, will be set to true if string was converted successfully
+     * \returns the distance unit
      * \see toString()
      */
     Q_INVOKABLE static QgsUnitTypes::DistanceUnit stringToDistanceUnit( const QString &string, bool *ok SIP_OUT = nullptr );
@@ -282,6 +283,7 @@ class CORE_EXPORT QgsUnitTypes
      * Converts a translated string to an areal unit.
      * \param string string representing an areal unit
      * \param ok optional boolean, will be set to true if string was converted successfully
+     * \returns the area unit
      * \see toString()
      */
     Q_INVOKABLE static AreaUnit stringToAreaUnit( const QString &string, bool *ok SIP_OUT = nullptr );
diff --git a/src/core/qgsvectorlayerjoinbuffer.h b/src/core/qgsvectorlayerjoinbuffer.h
index 53cb9f3a4477..cd69f1725b37 100644
--- a/src/core/qgsvectorlayerjoinbuffer.h
+++ b/src/core/qgsvectorlayerjoinbuffer.h
@@ -81,9 +81,11 @@ class CORE_EXPORT QgsVectorLayerJoinBuffer : public QObject, public QgsFeatureSi
 
     /**
      * Finds the vector join for a layer field index.
-      \param index this layers attribute index
-      \param fields fields of the vector layer (including joined fields)
-      \param sourceFieldIndex Output: field's index in source layer */
+     * \param index this layers attribute index
+     * \param fields fields of the vector layer (including joined fields)
+     * \param sourceFieldIndex Output: field's index in source layer
+     * \returns the vector layer join info
+     */
     const QgsVectorLayerJoinInfo *joinForFieldIndex( int index, const QgsFields &fields, int &sourceFieldIndex SIP_OUT ) const;
 
     /**
diff --git a/src/core/qgsziputils.h b/src/core/qgsziputils.h
index fa82360a91c2..73e689955556 100644
--- a/src/core/qgsziputils.h
+++ b/src/core/qgsziputils.h
@@ -38,12 +38,12 @@ namespace QgsZipUtils
   CORE_EXPORT bool isZipFile( const QString &filename );
 
   /**
-   * Unzip a zip file in an output directory. An error is returned if the zip
-   *  filename does not exist, the output directory does not exist or is
-   *  not writable.
+   * Unzip a zip file in an output directory.
    * \param zip The zip filename
    * \param dir The output directory
    * \param files The absolute path of unzipped files
+   * \returns false if the zip filename does not exist, the output directory
+   * does not exist or is not writable.
    * \since QGIS 3.0
    */
   CORE_EXPORT bool unzip( const QString &zip, const QString &dir, QStringList &files SIP_OUT );
diff --git a/src/gui/qgsexpressionlineedit.h b/src/gui/qgsexpressionlineedit.h
index bf92ce248f69..55d8eca04ad2 100644
--- a/src/gui/qgsexpressionlineedit.h
+++ b/src/gui/qgsexpressionlineedit.h
@@ -118,8 +118,9 @@ class GUI_EXPORT QgsExpressionLineEdit : public QWidget
     QString expression() const;
 
     /**
-      * Returns true if the current expression is valid.
+      * Determines if the current expression is valid.
       * \param expressionError will be set to any generated error message if specified
+      * \returns true if the current expression is valid.
       */
     bool isValidExpression( QString *expressionError SIP_OUT = nullptr ) const;