diff --git a/pyproject.toml b/pyproject.toml
index 091171d..75d0691 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@ pydantic-settings = "^2.6.0"
 httpx = "^0.28.0"
 structlog = "^25.0.0"
 pyyaml = ">=6.0.0"
-prometheus-client = "^0.25.0"
+prometheus-client = ">=0.25,<0.27"
 
 [tool.poetry.group.dev.dependencies]
 pytest = ">=8.3,<10.0"