diff --git a/mlx/backend/metal/scaled_dot_product_attention.cpp b/mlx/backend/metal/scaled_dot_product_attention.cpp
index 911984ef4..079a0baff 100644
--- a/mlx/backend/metal/scaled_dot_product_attention.cpp
+++ b/mlx/backend/metal/scaled_dot_product_attention.cpp
@@ -330,6 +330,7 @@ void ScaledDotProductAttention::eval_gpu(
     size_t str_oH = o.shape(3);
     size_t str_oL = o.shape(1) * str_oH;
     size_t str_oB = o.shape(2) * str_oL;
+    size_t data_size = o.shape(0) * str_oB;
 
     array::Flags flags{
         /* bool contiguous = */ 1,
@@ -339,7 +340,7 @@ void ScaledDotProductAttention::eval_gpu(
 
     o.set_data(
         allocator::malloc_or_wait(o.nbytes()),
-        o.data_size(),
+        data_size,
         {str_oB, str_oH, str_oL, str_oD},
         flags);