diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 43309d3..2003e0f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ jobs:
     
     strategy:
       matrix:
-        otp_version: [21,22,23]
+        otp_version: [20,21,22,23]
         os: [ubuntu-latest]
       
     container: