diff --git a/recipes/nextstrain-cli/meta.yaml b/recipes/nextstrain-cli/meta.yaml
index 6638b5d2251691..7fac237b317d74 100644
--- a/recipes/nextstrain-cli/meta.yaml
+++ b/recipes/nextstrain-cli/meta.yaml
@@ -37,12 +37,12 @@ requirements:
     - wrapt
     # nextstrain-cli requires boto3 but does not directly declare this
     # dependency, to avoid issues with pip dependency resolution with s3fs and
-    # botocore. We can declare the boto3 dependency and unpinned s3fs here,
-    # since Conda can resolve these dependency issues.
+    # botocore. We can declare the boto3 dependency and s3fs here, since Conda
+    # can resolve these dependency issues.
     # See: https://github.com/nextstrain/cli/blob/77c97bfecaf3dda84a8c20c343afc70cc6659f53/setup.py#L91-L98
     - fsspec
     - boto3
-    - s3fs
+    - s3fs >=2021.04.0
 
 test:
   requires: