diff --git a/src/mesa/drivers/dri/r300/r300_emit.c b/src/mesa/drivers/dri/r300/r300_emit.c
diff --git a/src/mesa/drivers/dri/r300/r300_vertprog.c b/src/mesa/drivers/dri/r300/r300_vertprog.c
index a40fb4f..d18b5fa 100644
--- a/src/mesa/drivers/dri/r300/r300_vertprog.c
+++ b/src/mesa/drivers/dri/r300/r300_vertprog.c
@@ -1283,6 +1283,9 @@ void r300SelectVertexShader(r300ContextPtr r300)
 	}
 	wanted_key.InputsRead = vpc->mesa_program.Base.InputsRead;
 	wanted_key.OutputsWritten = vpc->mesa_program.Base.OutputsWritten;
+	if (!(vpc->mesa_program.Base.OutputsWritten & (1 << VERT_RESULT_HPOS))) {
+	  wanted_key.OutputsWritten |= (1 << VERT_RESULT_HPOS);
+	}
 	if (vpc->mesa_program.IsPositionInvariant) {
 		/* we wan't position don't we ? */
 		wanted_key.InputsRead |= (1 << VERT_ATTRIB_POS);