diff --git a/src/gallium/drivers/nv40/nv40_draw.c b/src/gallium/drivers/nv40/nv40_draw.c
index ce0e0bc6f23..eb4f2395c48 100644
--- a/src/gallium/drivers/nv40/nv40_draw.c
+++ b/src/gallium/drivers/nv40/nv40_draw.c
@@ -335,7 +335,7 @@ nv40_state_vtxfmt_validate(struct nv40_context *nv40)
 		emit_attrib(nv40, 5, EMIT_1F, TGSI_SEMANTIC_FOG, 0);
 	}
 
-	emit_attrib(nv40, 0, EMIT_4F, TGSI_SEMANTIC_POSITION, 0);
+	emit_attrib(nv40, 0, EMIT_3F, TGSI_SEMANTIC_POSITION, 0);
 
 	return FALSE;
 }