diff --git a/bmi_geotiff/bmi.py b/bmi_geotiff/bmi.py
index 606b0c9..ce959c8 100644
--- a/bmi_geotiff/bmi.py
+++ b/bmi_geotiff/bmi.py
@@ -482,7 +482,7 @@ def get_value(self, name: str, dest: numpy.ndarray) -> numpy.ndarray:
         elif name == self._output_var_names[2]:
             dest[:] = self._da.rio.transform()
         else:
-            raise ValueError("get_value not available for {}.".format(name))
+            raise ValueError(f"get_value not available for {name}.")
 
         return dest
 
@@ -509,7 +509,7 @@ def get_value_at_indices(
             dest[:] = self.get_value_ptr(name).reshape(-1)[inds]
             return dest
         else:
-            raise ValueError("get_value_at_indices not available for {}.".format(name))
+            raise ValueError(f"get_value_at_indices not available for {name}.")
 
     def get_value_ptr(self, name: str) -> numpy.ndarray:
         """Get a reference to values of the given variable.
@@ -531,7 +531,7 @@ def get_value_ptr(self, name: str) -> numpy.ndarray:
         if name == self._output_var_names[0]:
             return self._da.values
         else:
-            raise ValueError("get_value_ptr not available for {}.".format(name))
+            raise ValueError(f"get_value_ptr not available for {name}.")
 
     def get_var_grid(self, name: str) -> int:
         """Get grid identifier for the given variable.