diff --git a/dev-requirements.txt b/dev-requirements.txt
index fa0ff2b2d..1bb8319ee 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -6,7 +6,7 @@ pyModbusTCP
 pyserial>=3.3
 pysnmp
 pysnmp-mibs
-pytest
+pytest==3.4.0
 pytest-cache
 pytest-cov
 pytest-isort