diff --git a/requirements_test.txt b/requirements_test.txt
index cc54c21c18b..5d22dbe13ba 100644
--- a/requirements_test.txt
+++ b/requirements_test.txt
@@ -3,7 +3,7 @@
 # new version
 flake8==3.3
 pylint==1.6.5
-mypy==0.520
+mypy==0.521
 pydocstyle==1.1.1
 coveralls>=1.1
 pytest>=2.9.2
diff --git a/requirements_test_all.txt b/requirements_test_all.txt
index 01f94812031..1bcd6a6eae2 100644
--- a/requirements_test_all.txt
+++ b/requirements_test_all.txt
@@ -4,7 +4,7 @@
 # new version
 flake8==3.3
 pylint==1.6.5
-mypy==0.520
+mypy==0.521
 pydocstyle==1.1.1
 coveralls>=1.1
 pytest>=2.9.2