diff --git a/tdescreensaver/kdesavers/pendulum.cpp b/tdescreensaver/kdesavers/pendulum.cpp
index d285d2cf..83f77d70 100644
--- a/tdescreensaver/kdesavers/pendulum.cpp
+++ b/tdescreensaver/kdesavers/pendulum.cpp
@@ -227,9 +227,9 @@ void PendulumGLWidget::initializeGL(void)
    glLoadIdentity();
    // set positon of light0
    GLfloat lightPos[4]=
-      {lightR * sin(lightTheta) * sin(lightPhi),
-       lightR * sin(lightTheta) * cos(lightPhi),
-       lightR * cos(lightTheta),
+      {(GLfloat)(lightR * sin(lightTheta) * sin(lightPhi)),
+       (GLfloat)(lightR * sin(lightTheta) * cos(lightPhi)),
+       (GLfloat)(lightR * cos(lightTheta)),
        0};
    glLightfv(GL_LIGHT0, GL_POSITION, lightPos);
    // set positon of light1