diff --git a/+af_tools/formatairfoilcoord.m b/+af_tools/formatairfoilcoord.m
index 78273d81208e96c8badc05787c7061a584d43082..77d3b44b447d4b6809edcf3247398756ad3c1f97 100644
--- a/+af_tools/formatairfoilcoord.m
+++ b/+af_tools/formatairfoilcoord.m
@@ -158,7 +158,7 @@ function Dat = formatairfoilcoord(varargin)
                 filename = [filename{1}, '-', outputFormat];
             end
             filename = appendextension(filename, '.dat');
-            filename = fullfile(Dat(i).path, filename);
+            filename = string(fullfile(Dat(i).path, filename));
             header = Dat(i).airfoil;
             savetodat(filename, header, Dat(i).array);
         end
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ef1d756fa34300960c1ae43af13d9c4318894ad..0601b31b7ae7e8b4830709aa00d6219abb0f7697 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,8 +22,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- **formatairfoilcoord**: fix issue with autosave
 - **xf2mat**: add error when input is not a proper xfoil/xflr5 result
-
 - **plotpolar**: fix issue when unavailable data
 
 ## [4.0.0] - 2022-06-09