diff --git a/test-requirements.txt b/test-requirements.txt
index e3f322d..bf4e32b 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,5 +1,5 @@
 pytest
-pytest-cov
+pytest-cov==2.8.1
 #pytest-datadir
 #pytest-mpl
 #pytest-regtest