diff --git a/pyproject.toml b/pyproject.toml
index aa261a6432b..7c1d5d4a60d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,7 +50,7 @@ dependencies = [
     "packaging",
     "pandas",
     "pluggy>=1.3.0",
-    "polars",
+    "polars>=1",
     "psutil",
     "pyarrow",  # extra dependency for pandas (parquet)
     "pydantic > 2",
diff --git a/src/ert/gui/ertwidgets/models/ertsummary.py b/src/ert/gui/ertwidgets/models/ertsummary.py
index 6e60dc8d2c6..4801ff67aab 100644
--- a/src/ert/gui/ertwidgets/models/ertsummary.py
+++ b/src/ert/gui/ertwidgets/models/ertsummary.py
@@ -37,6 +37,6 @@ def getParameters(self) -> tuple[list[str], int]:
     def getObservations(self) -> list[ObservationCount]:
         counts: list[ObservationCount] = []
         for df in self.ert_config.observations.values():
-            counts.extend(df.group_by("observation_key").count().to_dicts())  #  type: ignore
+            counts.extend(df.group_by("observation_key").len(name="count").to_dicts())  #  type: ignore
 
         return sorted(counts, key=lambda k: k["observation_key"].lower())