diff --git a/glib/gthreadprivate.h b/glib/gthreadprivate.h
index 74d37ba32..9de3d06ce 100644
--- a/glib/gthreadprivate.h
+++ b/glib/gthreadprivate.h
@@ -54,6 +54,12 @@ struct  _GRealThread
 /* Wrapper macro to call `futex_time64` and/or `futex` with simple
  * parameters and without returning the return value.
  *
+ * We expect futex to sometimes return EAGAIN due to the race
+ * between the caller checking the current value and deciding to
+ * do the futex op. To avoid splattering errno on success, we
+ * restore the original errno if EAGAIN is seen. See also:
+ *   https://gitlab.gnome.org/GNOME/glib/-/issues/3034
+ *
  * If the `futex_time64` syscall does not exist (`ENOSYS`), we retry again
  * with the normal `futex` syscall. This can happen if newer kernel headers
  * are used than the kernel that is actually running.
@@ -70,23 +76,37 @@ struct  _GRealThread
     if (res < 0 && errno == ENOSYS)                                              \
       {                                                                          \
         errno = saved_errno;                                                     \
-        syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__);              \
+        res = syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__);        \
+      }                                                                          \
+    if (res < 0 && errno == EAGAIN)                                              \
+      {                                                                          \
+        errno = saved_errno;                                                     \
       }                                                                          \
   }                                                                              \
   G_STMT_END
 #elif defined(__NR_futex_time64)
-#define g_futex_simple(uaddr, futex_op, ...)                           \
-  G_STMT_START                                                         \
-  {                                                                    \
-    syscall (__NR_futex_time64, uaddr, (gsize) futex_op, __VA_ARGS__); \
-  }                                                                    \
+#define g_futex_simple(uaddr, futex_op, ...)                                     \
+  G_STMT_START                                                                   \
+  {                                                                              \
+    int saved_errno = errno;                                                     \
+    int res = syscall (__NR_futex_time64, uaddr, (gsize) futex_op, __VA_ARGS__); \
+    if (res < 0 && errno == EAGAIN)                                              \
+      {                                                                          \
+        errno = saved_errno;                                                     \
+      }                                                                          \
+  }                                                                              \
   G_STMT_END
 #elif defined(__NR_futex)
-#define g_futex_simple(uaddr, futex_op, ...)                    \
-  G_STMT_START                                                  \
-  {                                                             \
-    syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__); \
-  }                                                             \
+#define g_futex_simple(uaddr, futex_op, ...)                              \
+  G_STMT_START                                                            \
+  {                                                                       \
+    int saved_errno = errno;                                              \
+    int res = syscall (__NR_futex, uaddr, (gsize) futex_op, __VA_ARGS__); \
+    if (res < 0 && errno == EAGAIN)                                       \
+      {                                                                   \
+        errno = saved_errno;                                              \
+      }                                                                   \
+  }                                                                       \
   G_STMT_END
 #else /* !defined(__NR_futex) && !defined(__NR_futex_time64) */
 #error "Neither __NR_futex nor __NR_futex_time64 are defined but were found by meson"
diff --git a/glib/tests/mutex.c b/glib/tests/mutex.c
index 2d0ef1ff3..bd484c59e 100644
--- a/glib/tests/mutex.c
+++ b/glib/tests/mutex.c
@@ -159,6 +159,63 @@ test_mutex5 (void)
     g_assert (owners[i] == NULL);
 }
 
+static gpointer
+test_mutex_errno_func (gpointer data)
+{
+  GMutex *m = data;
+
+  g_test_summary ("Validates that errno is not touched upon return");
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/3034");
+
+  for (unsigned int i = 0; i < 1000; i++)
+    {
+      errno = 0;
+      g_mutex_lock (m);
+      g_assert_cmpint (errno, ==, 0);
+
+      g_thread_yield ();
+
+      errno = 0;
+      g_mutex_unlock (m);
+      g_assert_cmpint (errno, ==, 0);
+
+      errno = 0;
+      if (g_mutex_trylock (m))
+        {
+          g_assert_cmpint (errno, ==, 0);
+
+          g_thread_yield ();
+
+          errno = 0;
+          g_mutex_unlock (m);
+          g_assert_cmpint (errno, ==, 0);
+        }
+    }
+
+  return NULL;
+}
+
+static void
+test_mutex_errno (void)
+{
+  gsize i;
+  GThread *threads[THREADS];
+  GMutex m;
+
+  g_mutex_init (&m);
+
+  for (i = 0; i < G_N_ELEMENTS (threads); i++)
+    {
+      threads[i] = g_thread_new ("test_mutex_errno",
+                                 test_mutex_errno_func, &m);
+    }
+
+  for (i = 0; i < G_N_ELEMENTS (threads); i++)
+    {
+      g_thread_join (threads[i]);
+    }
+}
+
 static gint count_to = 0;
 
 static gboolean
@@ -226,6 +283,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/thread/mutex3", test_mutex3);
   g_test_add_func ("/thread/mutex4", test_mutex4);
   g_test_add_func ("/thread/mutex5", test_mutex5);
+  g_test_add_func ("/thread/mutex/errno", test_mutex_errno);
 
     {
       guint i;