diff --git a/conda/environment.yml b/conda/environment.yml
index 424a0fc..0850cc4 100644
--- a/conda/environment.yml
+++ b/conda/environment.yml
@@ -12,7 +12,7 @@ dependencies:
   - scipy
   - sortedcontainers
   - sympy
-  - python-libsbml
+  - python-libsbml==5.20.1
   - lark
   - lark-parser
   - pytest