diff --git a/PQAnalysis/analysis/thermal_expansion/api.py b/PQAnalysis/analysis/thermal_expansion/api.py
index 8988892..34585f9 100644
--- a/PQAnalysis/analysis/thermal_expansion/api.py
+++ b/PQAnalysis/analysis/thermal_expansion/api.py
@@ -9,7 +9,6 @@
 from PQAnalysis.traj import MDEngineFormat
 from PQAnalysis.type_checking import runtime_type_checking
 from PQAnalysis.io.formats import FileWritingMode
-from PQAnalysis.types import Np1DNumberArray, Np2DNumberArray
 
 from .thermal_expansion import ThermalExpansion
 from .thermal_expansion_input_file_reader import ThermalExpansionInputFileReader
diff --git a/PQAnalysis/analysis/thermal_expansion/thermal_expansion_output_file_writer.py b/PQAnalysis/analysis/thermal_expansion/thermal_expansion_output_file_writer.py
index e835bad..04e8733 100644
--- a/PQAnalysis/analysis/thermal_expansion/thermal_expansion_output_file_writer.py
+++ b/PQAnalysis/analysis/thermal_expansion/thermal_expansion_output_file_writer.py
@@ -70,9 +70,10 @@ def write(
 
         thermal_expansion_data_mega = thermal_expansion_data * 1e6
         super().open()
-        angstrom = u'\u212b'
+        angstrom = '\u212b'
+        powert2three = '\u00b3'
         print(
-            f"# K {angstrom} {angstrom} {angstrom} {angstrom}³ 1/M 1/M 1/M 1/M",
+            f"# K {angstrom} {angstrom} {angstrom} {angstrom}{powert2three} 1/M 1/M 1/M 1/M",
             file=self.file
         )
         print(