diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6b697aa503..7fb23fe6c1 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -19,6 +19,7 @@ build:linux:
     stage: build
     script:
         - rustup toolchain add "$(cat rust-toolchain)"
+        - rustup component add rust-src
         - rustup show      # Print version info for debugging
         - make -j "$(nproc)" all
 
diff --git a/src/header/netdb/mod.rs b/src/header/netdb/mod.rs
index 8a510171a6..20816291f3 100644
--- a/src/header/netdb/mod.rs
+++ b/src/header/netdb/mod.rs
@@ -893,3 +893,15 @@ pub extern "C" fn gai_strerror(errcode: c_int) -> *const c_char {
     }
     .as_ptr()
 }
+
+#[no_mangle]
+pub extern "C" fn hstrerror(errcode: c_int) -> *const c_char {
+    match errcode {
+        HOST_NOT_FOUND => c_str!("Unknown hostname"),
+        NO_DATA => c_str!("No address for hostname"),
+        NO_RECOVERY => c_str!("Unknown server error"),
+        TRY_AGAIN => c_str!("Hostname lookup failure"),
+        _ => c_str!("Unknown error"),
+    }
+    .as_ptr()
+}