diff --git a/Cargo.toml b/Cargo.toml
index 00bad5c..1734c88 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -29,7 +29,7 @@ alloc = []
 std = []
 clock = ["time", "std"]
 wasmbind = ["wasm-bindgen", "js-sys"]
-__internal_bench = ["criterion"]
+__internal_bench = []
 
 [dependencies]
 time = { version = "0.1.39", optional = true }
@@ -37,8 +37,6 @@ num-integer = { version = "0.1.36", default-features = false }
 num-traits = { version = "0.2", default-features = false }
 rustc-serialize = { version = "0.3.20", optional = true }
 serde = { version = "1.0.99", default-features = false, optional = true }
-# technically a dev-dependency, but they can't be optional
-criterion = { version = "0.3", optional = true}
 
 [target.'cfg(all(target_arch = "wasm32", not(any(target_os = "emscripten", target_os = "wasi"))))'.dependencies]
 wasm-bindgen = { version = "0.2", optional = true }
@@ -49,16 +47,17 @@ serde_json = { version = "1", default-features = false }
 serde_derive = { version = "1", default-features = false }
 bincode = { version = "0.8.0" }
 num-iter = { version = "0.1.35", default-features = false }
+criterion = { version = "0.3" }
 doc-comment = "0.3"
 
 [target.'cfg(all(target_arch = "wasm32", not(any(target_os = "emscripten", target_os = "wasi"))))'.dev-dependencies]
 wasm-bindgen-test = "0.2"
 
 [package.metadata.docs.rs]
-all-features = true
+features = ["serde"]
 
 [package.metadata.playground]
-all-features = true
+features = ["serde"]
 
 [[bench]]
 name = "chrono"
diff --git a/benches/chrono.rs b/benches/chrono.rs
index 1bd66af..eede85c 100644
--- a/benches/chrono.rs
+++ b/benches/chrono.rs
@@ -6,7 +6,7 @@ extern crate criterion;
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
 use chrono::prelude::*;
-use chrono::{Utc, FixedOffset, DateTime, YearFlags};
+use chrono::{Utc, FixedOffset, DateTime, __BenchYearFlags};
 
 fn bench_datetime_parse_from_rfc2822(c: &mut Criterion) {
     c.bench_function("bench_datetime_parse_from_rfc2822", |b| {
@@ -56,7 +56,7 @@ fn bench_year_flags_from_year(c: &mut Criterion) {
     c.bench_function("bench_year_flags_from_year", |b|
                      b.iter(|| {
         for year in -999i32..1000 {
-            YearFlags::from_year(year);
+            __BenchYearFlags::from_year(year);
         }
     }));
 }
diff --git a/src/lib.rs b/src/lib.rs
index 12d24f7..9d85371 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -477,10 +477,7 @@ pub mod naive {
     //! (e.g. [`TimeZone`](../offset/trait.TimeZone.html)),
     //! but can be also used for the simpler date and time handling.
 
-    #[cfg(not(feature = "__internal_bench"))]
     mod internals;
-    #[cfg(feature = "__internal_bench")]
-    pub mod internals;
     mod date;
     mod isoweek;
     mod time;
@@ -494,6 +491,10 @@ pub mod naive {
     #[allow(deprecated)]
     pub use self::datetime::rustc_serialize::TsSeconds;
 
+    #[cfg(feature = "__internal_bench")]
+    #[doc(hidden)]
+    pub use self::internals::YearFlags as __BenchYearFlags;
+
 
     /// Serialization/Deserialization of naive types in alternate formats
     ///
@@ -514,7 +515,8 @@ pub mod format;
 mod round;
 
 #[cfg(feature = "__internal_bench")]
-pub use naive::internals::YearFlags;
+#[doc(hidden)]
+pub use naive::__BenchYearFlags;
 
 /// Serialization/Deserialization in alternate formats
 ///