diff --git a/src/gallium/auxiliary/tgsi/tgsi_exec.c b/src/gallium/auxiliary/tgsi/tgsi_exec.c
index f17d61c2c7c..8eaae4e46e3 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_exec.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_exec.c
@@ -3903,7 +3903,7 @@ exec_load_membuf(struct tgsi_exec_machine *mach,
    uint32_t unit = fetch_sampler_unit(mach, inst, 0);
 
    uint32_t size;
-   char *ptr;
+   const char *ptr;
    switch (inst->Src[0].Register.File) {
    case TGSI_FILE_MEMORY:
       ptr = mach->LocalMem;
@@ -3914,6 +3914,16 @@ exec_load_membuf(struct tgsi_exec_machine *mach,
       ptr = mach->Buffer->lookup(mach->Buffer, unit, &size);
       break;
 
+   case TGSI_FILE_CONSTANT:
+      if (unit < ARRAY_SIZE(mach->Consts)) {
+         ptr = mach->Consts[unit];
+         size = mach->ConstsSize[unit];
+      } else {
+         ptr = NULL;
+         size = 0;
+      }
+      break;
+
    default:
       unreachable("unsupported TGSI_OPCODE_LOAD file");
    }