diff --git a/build.rs b/build.rs
index a136b36..7875829 100644
--- a/build.rs
+++ b/build.rs
@@ -4,6 +4,8 @@ use std::env;
 
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rustc-check-cfg=cfg(fuzzing)");
+    println!("cargo:rustc-check-cfg=cfg(feature, values(\"folded_multiply\", \"specialize\"))");
     if let Some(true) = version_check::supports_feature("specialize") {
         println!("cargo:rustc-cfg=feature=\"specialize\"");
     }
diff --git a/src/random_state.rs b/src/random_state.rs
index ebd12fa..5bf2c14 100644
--- a/src/random_state.rs
+++ b/src/random_state.rs
@@ -537,7 +537,6 @@ impl <T> BuildHasher for RandomState<T> {
     /// implementation of [`Hash`].  The way to create a combined hash of
     /// multiple values is to call [`Hash::hash`] multiple times using the same
     /// [`Hasher`], not to call this method repeatedly and combine the results.
-    #[cfg(feature = "specialize")]
     #[inline]
     fn hash_one<V: Hash>(&self, x: V) -> u64 {
         use crate::specialize::CallHasher;
@@ -624,7 +623,6 @@ impl <T> BuildHasher for SmallState<T> {
     /// implementation of [`Hash`].  The way to create a combined hash of
     /// multiple values is to call [`Hash::hash`] multiple times using the same
     /// [`Hasher`], not to call this method repeatedly and combine the results.
-    #[cfg(feature = "specialize")]
     #[inline]
     fn hash_one<V: Hash>(&self, x: V) -> u64 {
         use crate::specialize::CallHasher;