diff --git a/backends/v3/src/radix.rs b/backends/v3/src/radix.rs
index 5bac1a31..c9ac12c2 100644
--- a/backends/v3/src/radix.rs
+++ b/backends/v3/src/radix.rs
@@ -16,6 +16,11 @@ pub struct RadixAllocator {
 
     /// Blocks that are immediately available for allocation.
     free_blocks: Vec<u32>,
+
+    #[allow(dead_code)]
+    // This isn't used because the prefix need to match without the windowing
+    // mecanism. This at worst is overallocating, not necessarily being wrong.
+    window_size: Option<u32>,
 }
 
 impl RadixAllocator {
@@ -25,9 +30,9 @@ impl RadixAllocator {
             "Radix tree allocator only works with block_size=1, was: {}",
             block_size
         );
-        if window_size.is_some() {
-            unimplemented!("Window size not supported in the prefix-caching block allocator yet");
-        }
+        // if window_size.is_some() {
+        //     unimplemented!("Window size not supported in the prefix-caching block allocator yet");
+        // }
 
         RadixAllocator {
             allocation_id: 0,
@@ -36,6 +41,7 @@ impl RadixAllocator {
 
             // Block 0 is reserved for health checks.
             free_blocks: (1..n_blocks).collect(),
+            window_size,
         }
     }
 
diff --git a/server/text_generation_server/layers/attention/cuda.py b/server/text_generation_server/layers/attention/cuda.py
index b3b7ea4f..7c415804 100644
--- a/server/text_generation_server/layers/attention/cuda.py
+++ b/server/text_generation_server/layers/attention/cuda.py
@@ -233,7 +233,7 @@ if ATTENTION == "flashinfer":
         causal=True,
         softcap=0.0,
     ):
-        assert window_size_left == -1, "Windowing is not supported with flash infer"
+        # assert window_size_left == -1, "Windowing is not supported with flash infer"
         from text_generation_server.layers.attention.flashinfer import (
             prefill_with_paged_kv_state,
         )
@@ -244,6 +244,7 @@ if ATTENTION == "flashinfer":
             paged_kv_cache=(key_cache, value_cache),
             logits_soft_cap=softcap,
             sm_scale=softmax_scale,
+            window_left=window_size_left,
         )
 
 elif V2: