diff --git a/src/initialize_dseries_toolbox.m b/src/initialize_dseries_toolbox.m
index 0d92f30ddc977a4e4ce03311258482d0e78a3391..a90657b7f3396134f4e89fd8e6b38bd83c6dbf31 100644
--- a/src/initialize_dseries_toolbox.m
+++ b/src/initialize_dseries_toolbox.m
@@ -28,15 +28,15 @@ dseries_src_root = strrep(which('initialize_dseries_toolbox'),'initialize_dserie
 % Check that the x13 binary is available
 nox13 = false;
 if isunix()
-    if ~(exist('../externals/x13/linux/64/x13', 'file') && exist('../externals/x13/linux/32/x13', 'file'))
+    if ~(exist([dseries_src_root '../externals/x13/linux/64/x13'], 'file') && exist([dseries_src_root '../externals/x13/linux/32/x13'], 'file'))
         nox13 = true;
     end
 elseif ismac()
-    if ~exist('../externals/x13/osx/64/x13', 'file')
+    if ~exist([dseries_src_root '../externals/x13/osx/64/x13'], 'file')
         nox13 = true;
     end
 elseif ispc()
-    if ~(exist('../externals/x13/windows/64/x13.exe', 'file') && exist('../externals/x13/windows/32/x13.exe', 'file'))
+    if ~(exist([dseries_src_root '../externals/x13/windows/64/x13.exe'], 'file') && exist([dseries_src_root '../externals/x13/windows/32/x13.exe'], 'file'))
         nox13 = true;
     end
 else