diff --git a/.travis.yml b/.travis.yml
index 72edf8a37..cbb554f0b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -116,6 +116,11 @@ before_install:
   - git fetch origin master:refs/remotes/origin/master
   - curl -L https://codeclimate.com/downloads/test-reporter/test-reporter-latest-linux-amd64 > ./cc-test-reporter
   - chmod +x ./cc-test-reporter
+  - pushd "$(mktemp -d)"
+  - git clone https://github.com/tomato42/python-ecdsa.git
+  - cd python-ecdsa
+  - python setup.py install
+  - popd
 
 install:
   - if [[ -e build-requirements-${TRAVIS_PYTHON_VERSION}.txt ]]; then travis_retry pip install -r build-requirements-${TRAVIS_PYTHON_VERSION}.txt; else travis_retry pip install -r build-requirements.txt; fi
diff --git a/build-requirements-2.7.txt b/build-requirements-2.7.txt
index 37007c166..c5a7e7d9d 100644
--- a/build-requirements-2.7.txt
+++ b/build-requirements-2.7.txt
@@ -3,5 +3,6 @@ coverage
 hypothesis
 coveralls
 pylint
-diff_cover
+mock
+diff_cover<2.5.0
 pytest>=4.6.5
diff --git a/build-requirements-3.3.txt b/build-requirements-3.3.txt
index 5b216fdab..cd6a9ed40 100644
--- a/build-requirements-3.3.txt
+++ b/build-requirements-3.3.txt
@@ -1,7 +1,7 @@
 enum34
-coverage
+coverage<5.0
 hypothesis<3.44
 coveralls
 pylint
-diff_cover
+diff_cover<2.5.0
 typed-ast<1.3.0
diff --git a/tlslite/keyexchange.py b/tlslite/keyexchange.py
index d31b9df96..42ccc91f0 100644
--- a/tlslite/keyexchange.py
+++ b/tlslite/keyexchange.py
@@ -23,6 +23,7 @@
 from .utils.x25519 import x25519, x448, X25519_G, X448_G, X25519_ORDER_SIZE, \
         X448_ORDER_SIZE
 from .utils.compat import int_types
+from .utils.codec import DecodeError
 
 
 class KeyExchange(object):
@@ -907,7 +908,7 @@ def calc_shared_key(self, private, peer_share):
             try:
                 ecdhYc = decodeX962Point(peer_share,
                                          curve)
-            except AssertionError:
+            except (AssertionError, DecodeError):
                 raise TLSIllegalParameterException("Invalid ECC point")
 
             S = ecdhYc * private
diff --git a/tlslite/utils/ecc.py b/tlslite/utils/ecc.py
index 87d875a4b..522a64e97 100644
--- a/tlslite/utils/ecc.py
+++ b/tlslite/utils/ecc.py
@@ -16,7 +16,9 @@ def decodeX962Point(data, curve=ecdsa.NIST256p):
     bytelength = getPointByteSize(curve)
     xCoord = bytesToNumber(parser.getFixBytes(bytelength))
     yCoord = bytesToNumber(parser.getFixBytes(bytelength))
-    return ecdsa.ellipticcurve.Point(curve.curve, xCoord, yCoord)
+    assert xCoord and yCoord
+    assert curve.curve.contains_point(xCoord, yCoord)
+    return ecdsa.ellipticcurve.PointJacobi(curve.curve, xCoord, yCoord, 1)
 
 def encodeX962Point(point):
     """Encode a point in X9.62 format"""