diff --git a/requests/adapters.py b/requests/adapters.py
index 4f2b23cf..fe9f5338 100644
--- a/requests/adapters.py
+++ b/requests/adapters.py
@@ -434,6 +434,9 @@ class HTTPAdapter(BaseAdapter):
             if isinstance(e.reason, ResponseError):
                 raise RetryError(e, request=request)
 
+            if isinstance(e.reason, _ProxyError):
+                raise ProxyError(e, request=request)
+
             raise ConnectionError(e, request=request)
 
         except ClosedPoolError as e:
diff --git a/tests/test_requests.py b/tests/test_requests.py
index 01811b8a..282a6679 100755
--- a/tests/test_requests.py
+++ b/tests/test_requests.py
@@ -21,7 +21,8 @@ from requests.compat import (
 from requests.cookies import cookiejar_from_dict, morsel_to_cookie
 from requests.exceptions import (
     ConnectionError, ConnectTimeout, InvalidSchema, InvalidURL,
-    MissingSchema, ReadTimeout, Timeout, RetryError, TooManyRedirects)
+    MissingSchema, ReadTimeout, Timeout, RetryError, TooManyRedirects,
+    ProxyError)
 from requests.models import PreparedRequest
 from requests.structures import CaseInsensitiveDict
 from requests.sessions import SessionRedirectMixin
@@ -358,6 +359,11 @@ class TestRequests:
         with pytest.raises(exception):
             requests.get(url, timeout=1)
 
+    def test_proxy_error(self):
+        # any proxy related error (address resolution, no route to host, etc) should result in a ProxyError
+        with pytest.raises(ProxyError):
+            requests.get('http://localhost:1', proxies={'http': 'non-resolvable-address'})
+
     def test_basicauth_with_netrc(self, httpbin):
         auth = ('user', 'pass')
         wrong_auth = ('wronguser', 'wrongpass')