diff --git a/changelog_entries/preprocess_non_cfg.md b/changelog_entries/preprocess_non_cfg.md
new file mode 100644
index 00000000000..73ce00b2f49
--- /dev/null
+++ b/changelog_entries/preprocess_non_cfg.md
@@ -0,0 +1,2 @@
+ ### Miscellaneous and Bug Fixes
+   * The command line `--preprocess` utility now accepts any filename, not just those ending .cfg.
diff --git a/src/serialization/preprocessor.cpp b/src/serialization/preprocessor.cpp
index c3d3ae8974b..253cdb9d269 100644
--- a/src/serialization/preprocessor.cpp
+++ b/src/serialization/preprocessor.cpp
@@ -1770,17 +1770,14 @@ void preprocess_resource(const std::string& res_name,
 
 		// Files in current directory
 		for(const std::string& file : files) {
-			preprocess_resource(file, defines_map, write_cfg, write_plain_cfg, parent_directory);
+			if(filesystem::ends_with(file, ".cfg")) {
+				preprocess_resource(file, defines_map, write_cfg, write_plain_cfg, parent_directory);
+			}
 		}
 
 		return;
 	}
 
-	// process only config files.
-	if(!filesystem::ends_with(res_name, ".cfg")) {
-		return;
-	}
-
 	LOG_PREPROC << "processing resource: " << res_name;
 
 	// disable filename encoding to get clear #line in cfg.plain