diff --git a/setup.m b/setup.m
index cc6d190..b9f8b02 100644
--- a/setup.m
+++ b/setup.m
@@ -1,17 +1,19 @@
 function setup()
     % to execute once after cloning the repo.
     createDefaultConfigFile();
 
     addpath(genpath(pwd));
 end
 
 
 
 function createDefaultConfigFile()
-    % should create a class to read/write variables in config file.
-    fid = fopen('config.txt','w');
-    fprintf(fid,'maxSCaseIDDigits = 3\n');    
-    fprintf(fid,'SCaseIDValidTypes = ''NP''\n');    
-    fprintf(fid,'pythonDir = ''/shoulder/methods/python/rcseg''\n');    
-    fprintf(fid,'dataDir = ''/shoulder/dataDev''\n');    
+    defaultConfig.maxSCaseIDDigits = 3;
+    defaultConfig.SCaseIDValidTypes = "NP";
+    defaultConfig.pythonDir = "/shoulder/methods/python/rcseg";
+    defaultConfig.dataDir = "/shoulder/dataDev";
+
+    fid = fopen('config.json','w');
+    fprintf(fid, replace(jsonencode(defaultConfig), ",", ",\n"));
+    fclose(fid);
 end
\ No newline at end of file