diff --git a/nion/utils/Converter.py b/nion/utils/Converter.py
index 1336d4f..3cbe2b5 100644
--- a/nion/utils/Converter.py
+++ b/nion/utils/Converter.py
@@ -135,12 +135,12 @@ def convert_back(self, formatted_value: typing.Optional[str]) -> typing.Optional
 class PhysicalValueToStringConverter(ConverterLike[float, str]):
     """ Convert between physical value represented by a float and a formatted string. """
 
-    def __init__(self, units: str, multiplier: float=1.0, format:typing.Optional[str]=None, pass_none:bool=False, fuzzy:bool=True) -> None:
+    def __init__(self, units: str, multiplier: float = 1.0, format: typing.Optional[str] = None, pass_none: bool = False) -> None:
         self.__units = units
         self.__multiplier = multiplier
         self.__format = format + " {:s}" if format else "{:g} {:s}"
         self.__pass_none = pass_none
-        self.__fuzzy = fuzzy
+        self.__float_to_string_converter = FloatToStringConverter(pass_none=self.__pass_none)
 
     def convert(self, value: typing.Optional[float]) -> typing.Optional[str]:
         """ Convert value to string using format string """
@@ -150,7 +150,7 @@ def convert(self, value: typing.Optional[float]) -> typing.Optional[str]:
 
     def convert_back(self, formatted_value: typing.Optional[str]) -> typing.Optional[float]:
         """ Convert string to value using standard float conversion """
-        value = FloatToStringConverter().convert_back(formatted_value)
+        value = self.__float_to_string_converter.convert_back(formatted_value)
         return value / self.__multiplier if value is not None else None
 
 
diff --git a/nion/utils/test/Converter_test.py b/nion/utils/test/Converter_test.py
index 25f4410..b3205ab 100644
--- a/nion/utils/test/Converter_test.py
+++ b/nion/utils/test/Converter_test.py
@@ -56,6 +56,26 @@ def test_date_to_string_converter(self) -> None:
         self.assertEqual(dt.replace(microsecond=0), converter.convert_back(converter.convert(dt.replace(microsecond=0))))
         self.assertEqual(dt.strftime(format), converter.convert(converter.convert_back(dt.strftime(format))))
 
+    def test_physical_value_to_str_converter_convert(self) -> None:
+        converter = Converter.PhysicalValueToStringConverter(units="m")
+        value = converter.convert(1.23)
+        self.assertEqual(value, "1.23 m")
+
+    def test_physical_value_to_str_converter_convert_back(self) -> None:
+        converter = Converter.PhysicalValueToStringConverter(units="m")
+        value = converter.convert_back("2.71 m")
+        self.assertEqual(value, 2.71)
+
+    def test_physical_value_to_str_converter_convert_back_with_none(self) -> None:
+        converter = Converter.PhysicalValueToStringConverter(units="m")
+        value = converter.convert_back(None)
+        self.assertEqual(value, 0.0)
+
+    def test_physical_value_to_str_converter_convert_back_pass_none(self) -> None:
+        converter = Converter.PhysicalValueToStringConverter(units="m", pass_none=True)
+        value = converter.convert_back(None)
+        self.assertEqual(value, None)
+
 
 if __name__ == '__main__':
     logging.getLogger().setLevel(logging.DEBUG)