diff --git a/README.md b/README.md
index 26815c5..b39f6a3 100644
--- a/README.md
+++ b/README.md
@@ -173,6 +173,7 @@ sum_to_x(10000)
 ```
 
 You will get `l = list(size=10000)` for the list, and `a = ndarray(shape=(10, 10), dtype=float64)` for the ndarray.
+The `custom_repr` are matched in order, if one condition matches, no further conditions will be checked.
 
 # Installation #
 
diff --git a/tox.ini b/tox.ini
index 94e91ca..2dfc609 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,6 +16,7 @@ description = Unit tests
 deps =
     pytest
     python_toolbox
+    numpy
 commands = pytest
 setenv =
     # until python_toolbox is fixed