diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6652aad73..d67039ce3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -62,6 +62,7 @@ jobs:
       - run: cd serde && cargo build --no-default-features
       - run: cd serde && cargo build --no-default-features --features alloc
       - run: cd serde && cargo build --no-default-features --features rc,alloc
+      - run: cd serde && cargo build --no-default-features --features unstable
       - run: cd serde && cargo test --features derive,rc,unstable
       - run: cd test_suite/no_std && cargo build
         if: matrix.os != 'windows'
diff --git a/serde/src/de/mod.rs b/serde/src/de/mod.rs
index a04ecf77d..b53206bdf 100644
--- a/serde/src/de/mod.rs
+++ b/serde/src/de/mod.rs
@@ -126,10 +126,13 @@ mod utf8;
 
 pub use self::ignored_any::IgnoredAny;
 
+#[cfg(all(feature = "unstable", not(feature = "std")))]
+#[doc(no_inline)]
+pub use core::error::Error as StdError;
 #[cfg(feature = "std")]
 #[doc(no_inline)]
 pub use std::error::Error as StdError;
-#[cfg(not(feature = "std"))]
+#[cfg(not(any(feature = "std", feature = "unstable")))]
 #[doc(no_inline)]
 pub use std_error::Error as StdError;