diff --git a/mbed/mbed.py b/mbed/mbed.py
index 8354a44e..d86b997f 100644
--- a/mbed/mbed.py
+++ b/mbed/mbed.py
@@ -1116,6 +1116,12 @@ def getlibs(self):
 
             for f in files:
                 if f.endswith('.lib') or f.endswith('.bld'):
+                    # If a library imports mbed-os and we're in including that
+                    # library in our app, skip the import of mbed-os: the app
+                    # will have already imported mbed-os.
+                    if f == 'mbed-os.lib' and self.pathtype() == 'library':
+                        action("Skipping redundant import of mbed-os in \"%s\"" % self.path)
+                        continue
                     repo = Repo.fromlib(os.path.join(root, f))
                     if repo:
                         yield repo