diff --git a/src/gallium/drivers/radeonsi/si_pm4.h b/src/gallium/drivers/radeonsi/si_pm4.h
index 3316cf77840..4ebc97cc260 100644
--- a/src/gallium/drivers/radeonsi/si_pm4.h
+++ b/src/gallium/drivers/radeonsi/si_pm4.h
@@ -54,7 +54,9 @@ struct si_pm4_state {
 
    /* commands for the DE */
    uint16_t max_dw;
-   uint32_t pm4[480];
+
+   /* This must be the last field because the array can continue after the structure. */
+   uint32_t pm4[64];
 };
 
 void si_pm4_cmd_add(struct si_pm4_state *state, uint32_t dw);
diff --git a/src/gallium/drivers/radeonsi/si_state.c b/src/gallium/drivers/radeonsi/si_state.c
index 8d242b85c40..293b9b81f8e 100644
--- a/src/gallium/drivers/radeonsi/si_state.c
+++ b/src/gallium/drivers/radeonsi/si_state.c
@@ -5383,11 +5383,19 @@ void si_init_cs_preamble_state(struct si_context *sctx, bool uses_reg_shadowing)
    struct si_screen *sscreen = sctx->screen;
    uint64_t border_color_va = sctx->border_color_buffer->gpu_address;
    bool has_clear_state = sscreen->info.has_clear_state;
-   struct si_pm4_state *pm4 = CALLOC_STRUCT(si_pm4_state);
+
+   struct si_cs_preamble {
+      struct si_pm4_state pm4;
+      uint32_t more_pm4[150]; /* Add more space because the preamble is large. */
+   };
+   struct si_pm4_state *pm4 = (struct si_pm4_state *)CALLOC_STRUCT(si_cs_preamble);
 
    if (!pm4)
       return;
 
+   /* Add all the space that we allocated. */
+   pm4->max_dw = sizeof(struct si_cs_preamble) - offsetof(struct si_cs_preamble, pm4.pm4);
+
    if (!uses_reg_shadowing) {
       si_pm4_cmd_add(pm4, PKT3(PKT3_CONTEXT_CONTROL, 1, 0));
       si_pm4_cmd_add(pm4, CC0_UPDATE_LOAD_ENABLES(1));