diff --git a/pyproject.toml b/pyproject.toml
index 7bca0b496c..61db5fe44c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -91,7 +91,7 @@ cite = [
 ]
 # Battery Parameter eXchange format
 bpx = [
-    "bpx>=0.5.0",
+    "bpx>=0.5.0,<0.6.0",
 ]
 # Low-overhead progress bars
 tqdm = [