diff --git a/src/mesa/swrast/s_feedback.c b/src/mesa/swrast/s_feedback.c
index 7afb3fa1ad1..2ebaaff3c19 100644
--- a/src/mesa/swrast/s_feedback.c
+++ b/src/mesa/swrast/s_feedback.c
@@ -77,7 +77,7 @@ static void feedback_vertex( GLcontext *ctx,
 
    index = v->index;
 
-   _mesa_feedback_vertex( ctx, win, color, index, tc );
+   _mesa_feedback_vertex( ctx, win, color, (GLfloat)index, tc );
 }