diff --git a/tox.ini b/tox.ini
index b7dda78..454af51 100644
--- a/tox.ini
+++ b/tox.ini
@@ -37,7 +37,7 @@ description =
 
 # The following provides some specific pinnings for key packages
 deps =
-    oldestdeps: numpy==1.17.*  # astropy LTS
+    oldestdeps: numpy==1.18.*  # astropy LTS
     olddeps: numpy==1.20.*  # something potentially problematic (see gh-101)
     devdeps: numpy>=0.0.dev0