diff --git a/src/scriptfile.c b/src/scriptfile.c
index 0d39f38..3508139 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -2156,11 +2156,7 @@
 
     if (p == NULL)
 	return NULL;
-#ifdef CASE_INSENSITIVE_FILENAME
-    prefix = strlow_save(p);
-#else
     prefix = vim_strsave(p);
-#endif
     if (prefix == NULL)
 	return NULL;
 
diff --git a/src/testdir/test_vim9_import.vim b/src/testdir/test_vim9_import.vim
index 79e5728..6c6911a 100644
--- a/src/testdir/test_vim9_import.vim
+++ b/src/testdir/test_vim9_import.vim
@@ -1485,6 +1485,15 @@
   END
   CheckScriptSuccess(lines)
 
+  if !has('fname_case')
+    lines =<< trim END
+        vim9script
+        import autoload 'CaseSensitive.vim'
+        import autoload 'casesensitive.vim'
+    END
+    CheckScriptFailure(lines, 'E1262:')
+  endif
+
   delete('Xdir', 'rf')
   &rtp = save_rtp
 enddef
diff --git a/src/version.c b/src/version.c
index d0d9b62..52b75a6 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4104,
+/**/
     4103,
 /**/
     4102,