diff --git a/llama/patches/0029-vulkan-Fix-FA-coopmat1-invalid-array-indexing.patch b/llama/patches/0029-vulkan-Fix-FA-coopmat1-invalid-array-indexing.patch
new file mode 100644
index 000000000..af4085440
--- /dev/null
+++ b/llama/patches/0029-vulkan-Fix-FA-coopmat1-invalid-array-indexing.patch
@@ -0,0 +1,30 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jeff Bolz <jbolz@nvidia.com>
+Date: Fri, 3 Oct 2025 04:52:46 -0500
+Subject: [PATCH] vulkan: Fix FA coopmat1 invalid array indexing (#16365)
+
+When computing sinks, the cm1 shader was looping r from 0 to Br rather than
+to rows_per_thread. I must have copied this from the scalar path (where it is
+correct), and somehow it wasn't causing failures on current drivers.
+---
+ ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp b/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
+index e76dbb4de..0507df2d8 100644
+--- a/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
++++ b/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
+@@ -358,8 +358,8 @@ void main() {
+     }
+ 
+     if ((p.mask_n_head_log2 & SINK_ENABLE_BIT) != 0) {
+-        [[unroll]] for (uint32_t r = 0; r < Br; ++r) {
+-            float sink = perElemOpGetSink(r, 0u, ACC_TYPE(0), iq2);
++        [[unroll]] for (uint32_t r = 0; r < rows_per_thread; ++r) {
++            float sink = perElemOpGetSink(tile_row(r), 0u, ACC_TYPE(0), iq2);
+ 
+             float ms = 1.0f;
+             float vs = 1.0f;
+-- 
+2.51.0.windows.1
+
diff --git a/ml/backend/ggml/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp b/ml/backend/ggml/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
index ddb1246e0..ef1ce0503 100644
--- a/ml/backend/ggml/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
+++ b/ml/backend/ggml/ggml/src/ggml-vulkan/vulkan-shaders/flash_attn_cm1.comp
@@ -356,8 +356,8 @@ void main() {
     }
 
     if ((p.mask_n_head_log2 & SINK_ENABLE_BIT) != 0) {
-        [[unroll]] for (uint32_t r = 0; r < Br; ++r) {
-            float sink = perElemOpGetSink(r, 0u, ACC_TYPE(0), iq2);
+        [[unroll]] for (uint32_t r = 0; r < rows_per_thread; ++r) {
+            float sink = perElemOpGetSink(tile_row(r), 0u, ACC_TYPE(0), iq2);
 
             float ms = 1.0f;
             float vs = 1.0f;