diff --git a/src/calibre/test_build.py b/src/calibre/test_build.py
index 50fb71430d..c25ed6de44 100644
--- a/src/calibre/test_build.py
+++ b/src/calibre/test_build.py
@@ -73,28 +73,39 @@ class BuildTest(unittest.TestCase):
         from html5_parser import parse
         parse('<p>xxx')
 
-    def test_imports(self):
+    def test_import_of_all_python_modules(self):
         import importlib
-        exclude = ['dbus_export.demo', 'dbus_export.gtk',  'upstream']
+        exclude_modules = {'calibre.gui2.dbus_export.demo', 'calibre.gui2.dbus_export.gtk'}
+        exclude_packages = {'calibre.devices.mtp.unix.upstream'}
         if not iswindows:
-            exclude.extend(['iphlpapi', 'windows', 'winreg', 'winusb'])
+            exclude_modules |= {'calibre.utils.iphlpapi', 'calibre.utils.open_with.windows', 'calibre.devices.winusb'}
+            exclude_packages |= {'calibre.utils.winreg'}
         if not isosx:
-            exclude.append('osx')
+            exclude_modules.add('calibre.utils.open_with.osx')
         if not islinux:
-            exclude.extend(['dbus', 'linux'])
+            exclude_modules |= {'calibre.utils.dbus_service', 'calibre.linux'}
+            exclude_packages.add('calibre.gui2.dbus_export')
         base = os.path.dirname(__file__)
-        trimpath = len(os.path.dirname(base)) + 1
+        import_base = os.path.dirname(base)
+        count = 0
         for root, dirs, files in os.walk(base):
-            for dir in dirs:
-                if not os.path.isfile(os.path.join(root, dir, '__init__.py')):
-                    dirs.remove(dir)
-            for file in files:
-                file, ext = os.path.splitext(file)
+            for d in dirs:
+                if not os.path.isfile(os.path.join(root, d, '__init__.py')):
+                    dirs.remove(d)
+            for fname in files:
+                module_name, ext = os.path.splitext(fname)
                 if ext != '.py':
                     continue
-                name = '.'.join(root[trimpath:].split(os.path.sep) + [file])
-                if not any(x for x in exclude if x in name):
-                    importlib.import_module(name)
+                path = os.path.join(root, module_name)
+                relpath = os.path.relpath(path, import_base).replace(os.sep, '/')
+                full_module_name = '.'.join(relpath.split('/'))
+                if full_module_name.endswith('.__init__'):
+                    full_module_name = full_module_name.rpartition('.')[0]
+                if full_module_name in exclude_modules or ('.' in full_module_name and full_module_name.rpartition('.')[0] in exclude_packages):
+                    continue
+                importlib.import_module(full_module_name)
+                count += 1
+        self.assertGreater(count, 1000)
 
     def test_plugins(self):
         exclusions = set()