diff --git a/tools/oldest_constraints.txt b/tools/oldest_constraints.txt
index 19d54655a..e1f058fd3 100644
--- a/tools/oldest_constraints.txt
+++ b/tools/oldest_constraints.txt
@@ -69,6 +69,7 @@ setuptools==39.0.1
 six==1.11.0
 
 # Ubuntu Focal constraints
+asn1crypto==0.24.0
 configobj==5.0.6
 parsedatetime==2.4