diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index bb88196780e..f8698929d4a 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -5284,6 +5284,8 @@ _mesa_sysval_to_semantic(unsigned sysval)
       return TGSI_SEMANTIC_BLOCK_ID;
    case SYSTEM_VALUE_NUM_WORK_GROUPS:
       return TGSI_SEMANTIC_GRID_SIZE;
+   case SYSTEM_VALUE_LOCAL_GROUP_SIZE:
+      return TGSI_SEMANTIC_BLOCK_SIZE;
 
    /* Unhandled */
    case SYSTEM_VALUE_LOCAL_INVOCATION_INDEX: