diff --git a/src/gallium/auxiliary/tgsi/tgsi_scan.c b/src/gallium/auxiliary/tgsi/tgsi_scan.c
index a23bb4067aa..b6c88af3a9e 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_scan.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_scan.c
@@ -238,6 +238,9 @@ tgsi_scan_shader(const struct tgsi_token *tokens,
                      else if (semName == TGSI_SEMANTIC_LAYER) {
                         info->writes_layer = TRUE;
                      }
+                     else if (semName == TGSI_SEMANTIC_PSIZE) {
+                        info->writes_psize = TRUE;
+                     }
                   }
 
                   if (procType == TGSI_PROCESSOR_FRAGMENT) {
diff --git a/src/gallium/auxiliary/tgsi/tgsi_scan.h b/src/gallium/auxiliary/tgsi/tgsi_scan.h
index b02b018b633..b50b650c801 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_scan.h
+++ b/src/gallium/auxiliary/tgsi/tgsi_scan.h
@@ -76,6 +76,7 @@ struct tgsi_shader_info
    boolean uses_vertexid;
    boolean uses_primid;
    boolean uses_frontface;
+   boolean writes_psize;
    boolean writes_viewport_index;
    boolean writes_layer;
    boolean is_msaa_sampler[PIPE_MAX_SAMPLERS];