diff --git a/src/mesa/tnl/t_vb_program.c b/src/mesa/tnl/t_vb_program.c
index f240e98387f..44fc63ad3ef 100644
--- a/src/mesa/tnl/t_vb_program.c
+++ b/src/mesa/tnl/t_vb_program.c
@@ -402,6 +402,9 @@ run_vp( struct gl_context *ctx, struct tnl_pipeline_stage *stage )
    unmap_textures(ctx, program);
 
    if (program->arb.IsPositionInvariant) {
+      /* make sure the inverse is up to date */
+      _math_matrix_analyse(&ctx->_ModelProjectMatrix);
+
       /* We need the exact same transform as in the fixed function path here
        * to guarantee invariance, depending on compiler optimization flags
        * results could be different otherwise.
diff --git a/src/mesa/tnl/t_vb_vertex.c b/src/mesa/tnl/t_vb_vertex.c
index 1309b465b78..60c624d77a7 100644
--- a/src/mesa/tnl/t_vb_vertex.c
+++ b/src/mesa/tnl/t_vb_vertex.c
@@ -158,6 +158,9 @@ static GLboolean run_vertex_stage( struct gl_context *ctx,
 				    VB->AttribPtr[_TNL_ATTRIB_POS]);
    }
 
+   /* make sure the inverse is up to date */
+   _math_matrix_analyse(&ctx->_ModelProjectMatrix);
+
    VB->ClipPtr = TransformRaw( &store->clip,
 			       &ctx->_ModelProjectMatrix,
 			       VB->AttribPtr[_TNL_ATTRIB_POS] );