diff --git a/lisa/trace.py b/lisa/trace.py
index 10a7c1ea2ec84440c6ee9ed717613f7497dbdc12..20bea0f8d259b5d4c4c656936d6033f29ae639dd 100644
--- a/lisa/trace.py
+++ b/lisa/trace.py
@@ -2038,7 +2038,7 @@ class TxtTraceParserBase(TraceParserBase):
 
         elif event in ('ipi_entry', 'ipi_exit'):
             df = df.with_columns(
-                pl.col('reason').str.strip_chars('()')
+                pl.col('reason').cast(pl.String).str.strip_chars('()').cast(pl.Categorical)
             )
 
         return df
diff --git a/setup.py b/setup.py
index fc25979ca740d15727448ead1822497613b0c4a3..536f6831b5aa60c59536240a36ad1954a6e1ed6f 100755
--- a/setup.py
+++ b/setup.py
@@ -136,10 +136,9 @@ if __name__ == "__main__":
             "holoviews >= 1.17",
             "panel",
             "colorcet",
-            # Force <1.7.0 until some issues are figured out:
-            # * problem on readthedocs
-            # * categorical issue: https://github.com/pola-rs/polars/issues/18717
-            "polars >= 1.0.0, < 2.0.0, < 1.7.0",
+            # Avoid:
+            # polars 1.7.0: https://github.com/pola-rs/polars/issues/18719
+            "polars >= 1.0.0, < 2.0.0, != 1.7.0",
             # Pandas >= 1.0.0 has support for new nullable dtypes
             # Pandas 1.2.0 has broken barplots:
             # https://github.com/pandas-dev/pandas/issues/38947