diff --git a/flashinfer/utils.py b/flashinfer/utils.py
index e2e820f221..44e8f1b762 100644
--- a/flashinfer/utils.py
+++ b/flashinfer/utils.py
@@ -408,6 +408,12 @@ def is_fa3_backend_supported(
         return False
     if use_fp16_qk_reductions:
         return False
+    # FA3 FP8 KV cache currently requires FP8 query.
+    if dtype_kv in {torch.float8_e4m3fn, torch.float8_e5m2} and dtype_q not in {
+        torch.float8_e4m3fn,
+        torch.float8_e5m2,
+    }:
+        return False
     return True