diff --git a/.circleci/config.yml b/.circleci/config.yml
index aa13f8bd..3e964086 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -129,6 +129,12 @@ jobs:
                   --manifest-path=systest/Cargo.toml \
                   <<# parameters.vendored >>--features vendored<</ parameters.vendored >> \
                   --target << parameters.target >>
+            - run: |
+                cargo test \
+                  --manifest-path=openssl-errors/Cargo.toml \
+                  <<# parameters.vendored >>--features openssl-sys/vendored<</ parameters.vendored >> \
+                  --target << parameters.target >> \
+                  <<# parameters.no_run >>--no-run<</ parameters.no_run >>
       - run: |
           ulimit -c unlimited
           export PATH=$OPENSSL_DIR/bin:$PATH
@@ -176,6 +182,10 @@ jobs:
           cargo run \
             --manifest-path=systest/Cargo.toml \
             <<# parameters.vendored >> --features vendored <</ parameters.vendored >>
+      - run: |
+          cargo run \
+            --manifest-path=openssl-errors/Cargo.toml \
+            <<# parameters.vendored >> --features openssl-sys/vendored <</ parameters.vendored >>
       - run: |
           PATH=/usr/local/opt/openssl/bin:$PATH
           cargo test \
diff --git a/Cargo.toml b/Cargo.toml
index 2ef99c17..3ad379d5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,2 +1,7 @@
 [workspace]
-members = ["openssl", "openssl-sys", "systest"]
+members = [
+    "openssl",
+    "openssl-errors",
+    "openssl-sys",
+    "systest",
+]
diff --git a/openssl-errors/Cargo.toml b/openssl-errors/Cargo.toml
new file mode 100644
index 00000000..9f08cf78
--- /dev/null
+++ b/openssl-errors/Cargo.toml
@@ -0,0 +1,13 @@
+[package]
+name = "openssl-errors"
+version = "0.1.0"
+authors = ["Steven Fackler <sfackler@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+libc = "0.2"
+
+openssl-sys = { version = "0.9.42", path = "../openssl-sys" }
+
+[dev-dependencies]
+openssl = { version = "0.10.19", path = "../openssl" }
diff --git a/openssl-errors/src/lib.rs b/openssl-errors/src/lib.rs
new file mode 100644
index 00000000..01a616d5
--- /dev/null
+++ b/openssl-errors/src/lib.rs
@@ -0,0 +1,213 @@
+use libc::{c_char, c_int};
+use std::ptr;
+use std::borrow::Cow;
+use std::marker::PhantomData;
+
+#[doc(hidden)]
+pub mod export {
+    pub use libc::{c_char, c_int};
+    pub use openssl_sys::{
+        init, ERR_get_next_error_library, ERR_load_strings, ERR_PACK, ERR_STRING_DATA,
+    };
+    pub use std::borrow::Cow;
+    pub use std::option::Option;
+    pub use std::ptr::null;
+    pub use std::sync::Once;
+}
+
+pub trait Library {
+    fn id() -> c_int;
+}
+
+pub struct Function<T>(c_int, PhantomData<T>);
+
+impl<T> Function<T> {
+    #[inline]
+    pub const fn from_raw(raw: c_int) -> Function<T> {
+        Function(raw, PhantomData)
+    }
+
+    #[inline]
+    pub const fn as_raw(&self) -> c_int {
+        self.0
+    }
+}
+
+pub struct Reason<T>(c_int, PhantomData<T>);
+
+impl<T> Reason<T> {
+    #[inline]
+    pub const fn from_raw(raw: c_int) -> Reason<T> {
+        Reason(raw, PhantomData)
+    }
+
+    #[inline]
+    pub const fn as_raw(&self) -> c_int {
+        self.0
+    }
+}
+
+/// This is not considered part of this crate's public API. It is subject to change at any time.
+///
+/// # Safety
+///
+/// `file` and `message` must be null-terminated.
+#[doc(hidden)]
+pub unsafe fn __put_error<T>(
+    func: Function<T>,
+    reason: Reason<T>,
+    file: &'static str,
+    line: u32,
+    message: Option<Cow<'static, str>>,
+) where
+    T: Library,
+{
+    openssl_sys::ERR_put_error(
+        T::id(),
+        func.as_raw(),
+        reason.as_raw(),
+        file.as_ptr() as *const c_char,
+        line as c_int,
+    );
+    let data = match message {
+        Some(Cow::Borrowed(s)) => Some((s.as_ptr() as *const c_char as *mut c_char, 0)),
+        Some(Cow::Owned(s)) => {
+            let ptr = openssl_sys::CRYPTO_malloc(
+                s.len() as _,
+                concat!(file!(), "\0").as_ptr() as *const c_char,
+                line!() as c_int,
+            ) as *mut c_char;
+            if ptr.is_null() {
+                None
+            } else {
+                ptr::copy_nonoverlapping(s.as_ptr(), ptr as *mut u8, s.len());
+                Some((ptr, openssl_sys::ERR_TXT_MALLOCED))
+            }
+        }
+        None => None
+    };
+    if let Some((ptr, flags)) = data {
+        openssl_sys::ERR_set_error_data(ptr, flags | openssl_sys::ERR_TXT_STRING);
+    }
+}
+
+#[macro_export]
+macro_rules! put_error {
+    ($function:expr, $reason:expr) => {
+        unsafe {
+            $crate::__put_error(
+                $function,
+                $reason,
+                concat!(file!(), "\0"),
+                line!(),
+                $crate::export::Option::None,
+            );
+        }
+    };
+    ($function:expr, $reason:expr, $message:expr) => {
+        unsafe {
+            $crate::__put_error(
+                $function,
+                $reason,
+                concat!(file!(), "\0"),
+                line!(),
+                $crate::export::Option::Some($crate::export::Cow::Borrowed(
+                    concat!($message, "\0"),
+                )),
+            );
+        }
+    };
+    ($function:expr, $reason:expr, $message:expr, $($args:tt)*) => {
+        unsafe {
+            $crate::__put_error(
+                $function,
+                $reason,
+                concat!(file!(), "\0"),
+                line!(),
+                $crate::export::Option::Some($crate::export::Cow::Owned(
+                    format!(concat!($message, "\0"), $($args)*)),
+                ),
+            );
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! openssl_errors {
+    ($(
+        $lib_vis:vis library $lib_name:ident($lib_str:expr) {
+            functions {
+                $(
+                    $func_name:ident($func_str:expr);
+                )*
+            }
+
+            reasons {
+                $(
+                    $reason_name:ident($reason_str:expr);
+                )*
+            }
+        }
+    )*) => {$(
+        $lib_vis enum $lib_name {}
+
+        impl $crate::Library for $lib_name {
+            fn id() -> $crate::export::c_int {
+                static INIT: $crate::export::Once = $crate::export::Once::new();
+                static mut LIB_NUM: $crate::export::c_int = 0;
+                static mut STRINGS: [$crate::export::ERR_STRING_DATA; 2 + $crate::openssl_errors!(@count $($func_name;)* $($reason_name;)*)] = [
+                    $crate::export::ERR_STRING_DATA {
+                        error: 0,
+                        string: concat!($lib_str, "\0").as_ptr() as *const $crate::export::c_char,
+                    },
+                    $(
+                        $crate::export::ERR_STRING_DATA {
+                            error: $crate::export::ERR_PACK(0, $lib_name::$func_name.as_raw(), 0),
+                            string: concat!($func_str, "\0").as_ptr() as *const $crate::export::c_char,
+                        },
+                    )*
+                    $(
+                        $crate::export::ERR_STRING_DATA {
+                            error: $crate::export::ERR_PACK(0, 0, $lib_name::$reason_name.as_raw()),
+                            string: concat!($reason_str, "\0").as_ptr() as *const $crate::export::c_char,
+                        },
+                    )*
+                    $crate::export::ERR_STRING_DATA {
+                        error: 0,
+                        string: $crate::export::null(),
+                    }
+                ];
+
+                unsafe {
+                    INIT.call_once(|| {
+                        $crate::export::init();
+                        LIB_NUM = $crate::export::ERR_get_next_error_library();
+                        STRINGS[0].error = $crate::export::ERR_PACK(LIB_NUM, 0, 0);
+                        $crate::export::ERR_load_strings(LIB_NUM, STRINGS.as_mut_ptr());
+                    });
+
+                    LIB_NUM
+                }
+            }
+        }
+
+        impl $lib_name {
+            $crate::openssl_errors!(@func_consts $lib_name; 1; $($func_name;)*);
+            $crate::openssl_errors!(@reason_consts $lib_name; 1; $($reason_name;)*);
+        }
+    )*};
+    (@func_consts $lib_name:ident; $n:expr; $name:ident; $($tt:tt)*) => {
+        pub const $name: $crate::Function<$lib_name> = $crate::Function::from_raw($n);
+        $crate::openssl_errors!(@func_consts $lib_name; $n + 1; $($tt)*);
+    };
+    (@func_consts $lib_name:ident; $n:expr;) => {};
+    (@reason_consts $lib_name:ident; $n:expr; $name:ident; $($tt:tt)*) => {
+        pub const $name: $crate::Reason<$lib_name> = $crate::Reason::from_raw($n);
+        $crate::openssl_errors!(@reason_consts $lib_name; $n + 1; $($tt)*);
+    };
+    (@reason_consts $lib_name:ident; $n:expr;) => {};
+    (@count $i:ident; $($tt:tt)*) => {
+        1 + $crate::openssl_errors!(@count $($tt)*)
+    };
+    (@count) => { 0 };
+}
diff --git a/openssl-errors/tests/test.rs b/openssl-errors/tests/test.rs
new file mode 100644
index 00000000..86dfc3b1
--- /dev/null
+++ b/openssl-errors/tests/test.rs
@@ -0,0 +1,54 @@
+use openssl::error::Error;
+
+openssl_errors::openssl_errors! {
+    library Test("test library") {
+        functions {
+            FOO("function foo");
+            BAR("function bar");
+        }
+
+        reasons {
+            NO_MILK("out of milk");
+            NO_BACON("out of bacon");
+        }
+    }
+}
+
+#[test]
+fn basic() {
+    openssl_errors::put_error!(Test::FOO, Test::NO_MILK);
+
+    let error = Error::get().unwrap();
+    assert_eq!(error.library().unwrap(), "test library");
+    assert_eq!(error.function().unwrap(), "function foo");
+    assert_eq!(error.reason().unwrap(), "out of milk");
+    assert_eq!(error.file(), "openssl-errors/tests/test.rs");
+    assert_eq!(error.line(), 19);
+    assert_eq!(error.data(), None);
+}
+
+#[test]
+fn static_data() {
+    openssl_errors::put_error!(Test::BAR, Test::NO_BACON, "foobar");
+
+    let error = Error::get().unwrap();
+    assert_eq!(error.library().unwrap(), "test library");
+    assert_eq!(error.function().unwrap(), "function bar");
+    assert_eq!(error.reason().unwrap(), "out of bacon");
+    assert_eq!(error.file(), "openssl-errors/tests/test.rs");
+    assert_eq!(error.line(), 32);
+    assert_eq!(error.data(), Some("foobar"));
+}
+
+#[test]
+fn dynamic_data() {
+    openssl_errors::put_error!(Test::BAR, Test::NO_MILK, "hello {}", "world");
+
+    let error = Error::get().unwrap();
+    assert_eq!(error.library().unwrap(), "test library");
+    assert_eq!(error.function().unwrap(), "function bar");
+    assert_eq!(error.reason().unwrap(), "out of milk");
+    assert_eq!(error.file(), "openssl-errors/tests/test.rs");
+    assert_eq!(error.line(), 45);
+    assert_eq!(error.data(), Some("hello world"));
+}