diff --git a/src/core/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c b/src/core/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
index 400957447..c3cba7c69 100644
--- a/src/core/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
+++ b/src/core/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c
@@ -5420,6 +5420,24 @@ parse_infiniband_p_key(shvarFile *ifcfg, int *out_p_key, char **out_parent, GErr
         return FALSE;
     }
 
+    /* The highest bit 0x8000 indicates full membership, which kernel always
+     * automatically sets.
+     *
+     * NetworkManager supports p-keys without the high bit set. That affects
+     * the interface name (nmp_utils_new_infiniband_name()) and is what
+     * we write to "create_child"/"delete_child" sysctl. Kernel will honor
+     * such p-keys for the interface name, but for other purposes it adds the
+     * highest bit. That makes using p-keys without the highest bit odd.
+     *
+     * Historically, /etc/sysconfig/network-scripts/ifup-ib would always add "|=0x8000".
+     * The reader does that too.
+     *
+     * Note that this means ifcfg cannot handle p-keys without the highest bit set,
+     * and when trying to store that to ifcfg format, the profile will be mangled/modified
+     * by the ifcg plugin (unlike keyfile backend, which preserves the original p-key value).
+     */
+    id |= 0x8000;
+
     *out_p_key  = id;
     *out_parent = g_steal_pointer(&physdev);
     return TRUE;
diff --git a/src/core/settings/plugins/ifcfg-rh/tests/test-ifcfg-rh.c b/src/core/settings/plugins/ifcfg-rh/tests/test-ifcfg-rh.c
index 017274748..bac5e93ed 100644
--- a/src/core/settings/plugins/ifcfg-rh/tests/test-ifcfg-rh.c
+++ b/src/core/settings/plugins/ifcfg-rh/tests/test-ifcfg-rh.c
@@ -8410,21 +8410,21 @@ test_read_ipoib(void)
     s_infiniband = nmtst_connection_assert_setting(connection, NM_TYPE_SETTING_INFINIBAND);
 
     pkey = nm_setting_infiniband_get_p_key(s_infiniband);
-    g_assert(pkey);
-    g_assert_cmpint(pkey, ==, 12);
+    g_assert_cmpint(pkey, ==, 0x800c);
 
     transport_mode = nm_setting_infiniband_get_transport_mode(s_infiniband);
-    g_assert(transport_mode);
     g_assert_cmpstr(transport_mode, ==, "connected");
 }
 
 static void
 test_write_infiniband(gconstpointer test_data)
 {
-    const int                     TEST_IDX   = GPOINTER_TO_INT(test_data);
-    nmtst_auto_unlinkfile char   *testfile   = NULL;
-    gs_unref_object NMConnection *connection = NULL;
-    gs_unref_object NMConnection *reread     = NULL;
+    const int                     TEST_IDX    = GPOINTER_TO_INT(test_data);
+    nmtst_auto_unlinkfile char   *testfile    = NULL;
+    gs_unref_object NMConnection *connection  = NULL;
+    gs_unref_object NMConnection *expected    = NULL;
+    gs_unref_object NMConnection *reread      = NULL;
+    gboolean                      reread_same = FALSE;
     NMSettingConnection          *s_con;
     NMSettingInfiniband          *s_infiniband;
     NMSettingIPConfig            *s_ip4;
@@ -8434,6 +8434,7 @@ test_write_infiniband(gconstpointer test_data)
     NMIPAddress *addr;
     GError      *error          = NULL;
     const char  *interface_name = NULL;
+    int          p_key;
 
     connection = nm_simple_connection_new();
 
@@ -8449,14 +8450,21 @@ test_write_infiniband(gconstpointer test_data)
                  NM_SETTING_INFINIBAND_SETTING_NAME,
                  NULL);
 
-    if (NM_IN_SET(TEST_IDX, 1, 3))
-        interface_name = "ib0.000c";
+    if (NM_IN_SET(TEST_IDX, 1, 2))
+        p_key = nmtst_get_rand_bool() ? 0x000c : 0x800c;
+    else
+        p_key = -1;
+
+    if (NM_IN_SET(TEST_IDX, 1, 3)) {
+        if (p_key >= 0x8000)
+            interface_name = "ib0.800c";
+    }
 
     g_object_set(s_con, NM_SETTING_CONNECTION_INTERFACE_NAME, interface_name, NULL);
 
     s_infiniband = _nm_connection_new_setting(connection, NM_TYPE_SETTING_INFINIBAND);
     g_object_set(s_infiniband, NM_SETTING_INFINIBAND_TRANSPORT_MODE, "connected", NULL);
-    if (NM_IN_SET(TEST_IDX, 1, 2)) {
+    if (p_key == -1) {
         g_object_set(s_infiniband,
                      NM_SETTING_INFINIBAND_MAC_ADDRESS,
                      mac,
@@ -8466,7 +8474,7 @@ test_write_infiniband(gconstpointer test_data)
     } else {
         g_object_set(s_infiniband,
                      NM_SETTING_INFINIBAND_P_KEY,
-                     12,
+                     p_key,
                      NM_SETTING_INFINIBAND_PARENT,
                      "ib0",
                      NULL);
@@ -8495,13 +8503,32 @@ test_write_infiniband(gconstpointer test_data)
 
     nmtst_assert_connection_verifies(connection);
 
-    _writer_new_connection(connection, TEST_SCRATCH_DIR, &testfile);
+    if (p_key != -1 && p_key < 0x8000) {
+        expected = nm_simple_connection_new_clone(connection);
+        g_object_set(nm_connection_get_setting(expected, NM_TYPE_SETTING_INFINIBAND),
+                     NM_SETTING_INFINIBAND_P_KEY,
+                     (int) (p_key | 0x8000),
+                     NULL);
+    } else
+        expected = g_object_ref(connection);
 
-    reread = _connection_from_file(testfile, NULL, TYPE_INFINIBAND, NULL);
-
-    nmtst_assert_connection_equals(connection, TRUE, reread, FALSE);
+    _writer_new_connection_reread(connection,
+                                  TEST_SCRATCH_DIR,
+                                  &testfile,
+                                  NO_EXPECTED,
+                                  &reread,
+                                  &reread_same);
+    _assert_reread_same(expected, reread);
+    if (p_key == -1 || p_key > 0x8000)
+        g_assert(reread_same);
+    else
+        g_assert(!reread_same);
 
     g_assert_cmpstr(interface_name, ==, nm_connection_get_interface_name(reread));
+    g_assert_cmpint(nm_setting_infiniband_get_p_key(
+                        _nm_connection_get_setting(reread, NM_TYPE_SETTING_INFINIBAND)),
+                    ==,
+                    p_key == -1 ? -1 : (p_key | 0x8000));
 }
 
 static void