diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index a2375353..1247cac3 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -61,6 +61,20 @@ jobs:
         run: ./ci/h2spec.sh
         if: matrix.rust == 'stable'
 
+  unexpected-cfgs:
+    runs-on: ubuntu-latest
+    needs: [style]
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo check --all-features
+        env:
+          RUSTFLAGS: >-
+            -D unexpected_cfgs
+            --cfg h2_internal_check_unexpected_cfgs
+            --check-cfg=cfg(h2_internal_check_unexpected_cfgs,fuzzing)
+
   #clippy_check:
   #  runs-on: ubuntu-latest
   #  steps:
diff --git a/src/lib.rs b/src/lib.rs
index fd7782f8..5f596653 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -85,6 +85,7 @@
     clippy::undocumented_unsafe_blocks
 )]
 #![allow(clippy::type_complexity, clippy::manual_range_contains)]
+#![cfg_attr(not(h2_internal_check_unexpected_cfgs), allow(unexpected_cfgs))]
 #![cfg_attr(test, deny(warnings))]
 
 macro_rules! proto_err {