diff --git a/poky/meta/classes/externalsrc.bbclass b/poky/meta/classes/externalsrc.bbclass
index dd09395..64e94e3 100644
--- a/poky/meta/classes/externalsrc.bbclass
+++ b/poky/meta/classes/externalsrc.bbclass
@@ -190,6 +190,7 @@
     import shutil
     import subprocess
     import tempfile
+    import hashlib
 
     s_dir = srcdir or d.getVar('EXTERNALSRC')
     git_dir = None
@@ -197,6 +198,10 @@
     try:
         git_dir = os.path.join(s_dir,
             subprocess.check_output(['git', '-C', s_dir, 'rev-parse', '--git-dir'], stderr=subprocess.DEVNULL).decode("utf-8").rstrip())
+        top_git_dir = os.path.join(s_dir, subprocess.check_output(['git', '-C', d.getVar("TOPDIR"), 'rev-parse', '--git-dir'],
+            stderr=subprocess.DEVNULL).decode("utf-8").rstrip())
+        if git_dir == top_git_dir:
+            git_dir = None
     except subprocess.CalledProcessError:
         pass
 
@@ -210,7 +215,16 @@
             env = os.environ.copy()
             env['GIT_INDEX_FILE'] = tmp_index.name
             subprocess.check_output(['git', 'add', '-A', '.'], cwd=s_dir, env=env)
-            sha1 = subprocess.check_output(['git', 'write-tree'], cwd=s_dir, env=env).decode("utf-8")
+            git_sha1 = subprocess.check_output(['git', 'write-tree'], cwd=s_dir, env=env).decode("utf-8")
+            submodule_helper = subprocess.check_output(['git', 'submodule--helper', 'list'], cwd=s_dir, env=env).decode("utf-8")
+            for line in submodule_helper.splitlines():
+                module_dir = os.path.join(s_dir, line.rsplit(maxsplit=1)[1])
+                proc = subprocess.Popen(['git', 'add', '-A', '.'], cwd=module_dir, env=env, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+                proc.communicate()
+                proc = subprocess.Popen(['git', 'write-tree'], cwd=module_dir, env=env, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
+                stdout, _ = proc.communicate()
+                git_sha1 += stdout.decode("utf-8")
+            sha1 = hashlib.sha1(git_sha1.encode("utf-8")).hexdigest()
         with open(oe_hash_file, 'w') as fobj:
             fobj.write(sha1)
         ret = oe_hash_file + ':True'