diff --git a/pyproject.toml b/pyproject.toml
index ded50f8f25b9ef0ea146408920e62c81c5329d4d..56544f738ff8e0c10580844c1506d7e6ad73b6a6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,6 +41,7 @@ dependencies = [
   "torch>=1.8",
   "torchvision>=0.10",
   "lightning>=2.0.3",
+  "pydantic <2.0,>=1.7.4",  # temporary, until issue #31 is fixed
   "tensorboard",
 ]