diff --git a/requirements.txt b/requirements.txt
index 9be1110..faeda44 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 boto3>=1.36
 shapely>=2.0
 pycairo>=1.27,<2.0
+pyiem>=1.23,<2.0