diff --git a/src/uu/stdbuf/src/libstdbuf/Cargo.toml b/src/uu/stdbuf/src/libstdbuf/Cargo.toml
index df9e5a81a03..9e8a5a64bb3 100644
--- a/src/uu/stdbuf/src/libstdbuf/Cargo.toml
+++ b/src/uu/stdbuf/src/libstdbuf/Cargo.toml
@@ -14,7 +14,6 @@ rust-version.workspace = true
 name = "stdbuf"
 path = "src/libstdbuf.rs"
 crate-type = ["cdylib"]
-test = false
 
 [dependencies]
 ctor = { workspace = true }
diff --git a/src/uu/stdbuf/src/libstdbuf/src/libstdbuf.rs b/src/uu/stdbuf/src/libstdbuf/src/libstdbuf.rs
index f1aa4dcb621..3875fa69fd6 100644
--- a/src/uu/stdbuf/src/libstdbuf/src/libstdbuf.rs
+++ b/src/uu/stdbuf/src/libstdbuf/src/libstdbuf.rs
@@ -24,9 +24,9 @@ pub unsafe extern "C" fn __stdbuf_get_stdin() -> *mut FILE {
     #[cfg(any(target_vendor = "apple", target_os = "freebsd"))]
     {
         unsafe extern "C" {
-            fn __stdinp() -> *mut FILE;
+            static mut __stdinp: *mut FILE;
         }
-        unsafe { __stdinp() }
+        unsafe { __stdinp }
     }
 
     #[cfg(target_os = "openbsd")]
@@ -87,9 +87,9 @@ pub unsafe extern "C" fn __stdbuf_get_stdout() -> *mut FILE {
     #[cfg(any(target_vendor = "apple", target_os = "freebsd"))]
     {
         unsafe extern "C" {
-            fn __stdoutp() -> *mut FILE;
+            static mut __stdoutp: *mut FILE;
         }
-        unsafe { __stdoutp() }
+        unsafe { __stdoutp }
     }
 
     #[cfg(target_os = "openbsd")]
@@ -150,9 +150,9 @@ pub unsafe extern "C" fn __stdbuf_get_stderr() -> *mut FILE {
     #[cfg(any(target_vendor = "apple", target_os = "freebsd"))]
     {
         unsafe extern "C" {
-            fn __stderrp() -> *mut FILE;
+            static mut __stderrp: *mut FILE;
         }
-        unsafe { __stderrp() }
+        unsafe { __stderrp }
     }
 
     #[cfg(target_os = "openbsd")]
@@ -188,7 +188,7 @@ pub unsafe extern "C" fn __stdbuf_get_stderr() -> *mut FILE {
             fn __getreent() -> *mut _reent;
         }
 
-        unsafe { (*__getreent())._stdin }
+        unsafe { (*__getreent())._stderr }
     }
 
     #[cfg(not(any(
@@ -249,3 +249,18 @@ pub unsafe extern "C" fn __stdbuf() {
         set_buffer(unsafe { __stdbuf_get_stdout() }, &val);
     }
 }
+
+#[cfg(all(test, unix))]
+mod tests {
+    use super::*;
+
+    // Each getter must return its own stream, not another one.
+    #[test]
+    fn test_stream_getters_return_matching_streams() {
+        unsafe {
+            assert_eq!(fileno(__stdbuf_get_stdin()), libc::STDIN_FILENO);
+            assert_eq!(fileno(__stdbuf_get_stdout()), libc::STDOUT_FILENO);
+            assert_eq!(fileno(__stdbuf_get_stderr()), libc::STDERR_FILENO);
+        }
+    }
+}