diff --git a/environment.yml b/environment.yml
index c4b2ec500205a864828cb89b52b7a1b82341e615..fd6119ad8dc77461ad220cadf76747a518b47294 100644
--- a/environment.yml
+++ b/environment.yml
@@ -24,6 +24,7 @@ dependencies:
   - bioconda::bioconductor-hitc=1.32.0
   - conda-forge::r-optparse=1.6.6
   - bioconda::ucsc-bedgraphtobigwig=357
+  - conda-forge::cython=0.29.19
   - pip:
     - cooltools==0.3.2
     - fanc==0.8.30
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