diff --git a/src/blr/envs/manta.yml b/src/blr/envs/manta.yml
index 000dd6b8..34535842 100644
--- a/src/blr/envs/manta.yml
+++ b/src/blr/envs/manta.yml
@@ -4,6 +4,6 @@ channels:
   - bioconda
   - nodefaults
 dependencies:
-  - bioconda::manta=1.6.0
+  - bioconda::manta[version=1.6.0, build=*_3]
   - bioconda::samtools=1.12
-  - conda-forge::python<3
+  - conda-forge::python=2.7*