diff --git a/pyext/GModelSpatialRadialDisk.i b/pyext/GModelSpatialRadialDisk.i
index dc6e5e8..97896c3 100644
--- a/pyext/GModelSpatialRadialDisk.i
+++ b/pyext/GModelSpatialRadialDisk.i
@@ -66,9 +66,21 @@ public:
 
 /***********************************************************************//**
  * @brief GModelSpatialRadialDisk class extension
+ *
+ * The eval(GSkyDir&) and eval_gradients(GSkyDir&) need to be defined in the
+ * extension to force swig to build also the interface for these methods that
+ * are implemented in the base class only. It's not clear to me why these
+ * methods are not inherited automatically. Maybe this could also be handled
+ * by a %typemap(typecheck) construct.
  ***************************************************************************/
 %extend GModelSpatialRadialDisk {
     GModelSpatialRadialDisk copy() {
         return (*self);
     }
+    double eval(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval(srcDir);
+    }
+    double eval_gradients(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval_gradients(srcDir);
+    }
 };
diff --git a/pyext/GModelSpatialRadialGauss.i b/pyext/GModelSpatialRadialGauss.i
index 414108c..b2ebd9d 100644
--- a/pyext/GModelSpatialRadialGauss.i
+++ b/pyext/GModelSpatialRadialGauss.i
@@ -63,9 +63,21 @@ public:
 
 /***********************************************************************//**
  * @brief GModelSpatialRadialGauss class extension
+ *
+ * The eval(GSkyDir&) and eval_gradients(GSkyDir&) need to be defined in the
+ * extension to force swig to build also the interface for these methods that
+ * are implemented in the base class only. It's not clear to me why these
+ * methods are not inherited automatically. Maybe this could also be handled
+ * by a %typemap(typecheck) construct.
  ***************************************************************************/
 %extend GModelSpatialRadialGauss {
     GModelSpatialRadialGauss copy() {
         return (*self);
     }
+    double eval(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval(srcDir);
+    }
+    double eval_gradients(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval_gradients(srcDir);
+    }
 };
diff --git a/pyext/GModelSpatialRadialShell.i b/pyext/GModelSpatialRadialShell.i
index c9858d6..7bea8bf 100644
--- a/pyext/GModelSpatialRadialShell.i
+++ b/pyext/GModelSpatialRadialShell.i
@@ -68,9 +68,21 @@ public:
 
 /***********************************************************************//**
  * @brief GModelSpatialRadialShell class extension
+ *
+ * The eval(GSkyDir&) and eval_gradients(GSkyDir&) need to be defined in the
+ * extension to force swig to build also the interface for these methods that
+ * are implemented in the base class only. It's not clear to me why these
+ * methods are not inherited automatically. Maybe this could also be handled
+ * by a %typemap(typecheck) construct.
  ***************************************************************************/
 %extend GModelSpatialRadialShell {
     GModelSpatialRadialShell copy() {
         return (*self);
     }
+    double eval(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval(srcDir);
+    }
+    double eval_gradients(const GSkyDir& srcDir) const {
+        return self->GModelSpatialRadial::eval_gradients(srcDir);
+    }
 };