diff --git a/tests/kalman/likelihood/test_kalman_mex.m b/tests/kalman/likelihood/test_kalman_mex.m
index 28aad0680..533a52b03 100644
--- a/tests/kalman/likelihood/test_kalman_mex.m
+++ b/tests/kalman/likelihood/test_kalman_mex.m
@@ -1,6 +1,11 @@
 debug = true;
 
-source_dir = getenv('source_root');
+if debug
+    source_dir = fileparts(mfilename('fullpath'));
+    source_dir = sprintf('%s/../../../', source_dir)
+else
+    source_dir = getenv('source_root');
+end
 
 mex_path = [source_dir filesep 'build-matlab'];
 addpath(mex_path);
@@ -40,36 +45,36 @@ Experience.kalman_filter_matlab = kalman_filter_matlab;
 Experience.kalman_filter_mex = kalman_filter_mex;
 
 try
-   flag = compare_kalman_mex(Experience);
-   if (flag)
-      testFailed = testFailed+1;
-      if debug
-         dprintf('MEX and MATLAB Kalman filters lead to different results')
-      end
-   end
+    flag = compare_kalman_mex(Experience);
+    if (flag)
+        testFailed = testFailed+1;
+        if debug
+            dprintf('MEX and MATLAB Kalman filters lead to different results')
+        end
+    end
 catch
-   testFailed = testFailed+1;
-   if debug
-      dprintf('Comparison between MEX and MATLAB Kalman filters failed')
-   end
+    testFailed = testFailed+1;
+    if debug
+        dprintf('Comparison between MEX and MATLAB Kalman filters failed')
+    end
 end
 
 dprintf('Test 2: measurement error with diagonal variance-covariance matrix')
 Experience.MeasurementErrors = 1;
 
 try
-   flag = compare_kalman_mex(Experience);
-   if (flag)
-      testFailed = testFailed+1;
-      if debug
-         dprintf('MEX and MATLAB Kalman filters lead to different results')
-      end
-   end
+    flag = compare_kalman_mex(Experience);
+    if (flag)
+        testFailed = testFailed+1;
+        if debug
+            dprintf('MEX and MATLAB Kalman filters lead to different results')
+        end
+    end
 catch
-   testFailed = testFailed+1;
-   if debug
-      dprintf('Comparison between MEX and MATLAB Kalman filters failed')
-   end
+    testFailed = testFailed+1;
+    if debug
+        dprintf('Comparison between MEX and MATLAB Kalman filters failed')
+    end
 end
 
 dprintf('Test 3: measurement error with general variance-covariance matrix')
@@ -98,4 +103,6 @@ t1 = clock;
 
 fprintf('\n*** Elapsed time (in seconds): %.1f\n\n', etime(t1, t0));
 
-quit(testFailed > 0)
\ No newline at end of file
+if ~debug
+    quit(testFailed > 0)
+end