diff --git a/src/gallium/drivers/svga/svga_tgsi_decl_sm30.c b/src/gallium/drivers/svga/svga_tgsi_decl_sm30.c
index 137afd60583..42d6f489bc5 100644
--- a/src/gallium/drivers/svga/svga_tgsi_decl_sm30.c
+++ b/src/gallium/drivers/svga/svga_tgsi_decl_sm30.c
@@ -319,6 +319,7 @@ ps30_input(struct svga_shader_emitter *emit,
 /**
  * Process a PS output declaration.
  * Note that we don't actually emit a SVGA3DOpDcl for PS outputs.
+ * \idx  register index, such as OUT[2] (not semantic index)
  */
 static boolean
 ps30_output(struct svga_shader_emitter *emit,
@@ -344,9 +345,9 @@ ps30_output(struct svga_shader_emitter *emit,
             if (semantic.Index == 0) {
                unsigned i;
                for (i = 0; i < emit->key.fkey.write_color0_to_n_cbufs; i++) {
-                  emit->output_map[i] = dst_register(SVGA3DREG_TEMP,
+                  emit->output_map[idx+i] = dst_register(SVGA3DREG_TEMP,
                                                      emit->nr_hw_temp++);
-                  emit->temp_color_output[i] = emit->output_map[i];
+                  emit->temp_color_output[i] = emit->output_map[idx+i];
                   emit->true_color_output[i] = dst_register(SVGA3DREG_COLOROUT,
                                                             i);
                }
diff --git a/src/gallium/drivers/svga/svga_tgsi_emit.h b/src/gallium/drivers/svga/svga_tgsi_emit.h
index d31b866928a..53f93de28d3 100644
--- a/src/gallium/drivers/svga/svga_tgsi_emit.h
+++ b/src/gallium/drivers/svga/svga_tgsi_emit.h
@@ -99,6 +99,7 @@ struct svga_shader_emitter
    unsigned label[32];
    unsigned nr_labels;
 
+   /** input/output register mappings, indexed by register number */
    struct src_register input_map[PIPE_MAX_ATTRIBS];
    SVGA3dShaderDestToken output_map[PIPE_MAX_ATTRIBS];
 
@@ -119,7 +120,7 @@ struct svga_shader_emitter
    /* shared output for depth and fog */
    SVGA3dShaderDestToken vs_depth_fog;
 
-   /* PS output colors */
+   /* PS output colors (indexed by color semantic index) */
    SVGA3dShaderDestToken temp_color_output[PIPE_MAX_COLOR_BUFS];
    SVGA3dShaderDestToken true_color_output[PIPE_MAX_COLOR_BUFS];