diff --git a/common.cpp b/common.cpp
index cb4a3da..8dae5b7 100644
--- a/common.cpp
+++ b/common.cpp
@@ -1,6 +1,7 @@
 #include "common.h"
 
 #include <fstream>
+#include <set>
 
 #include <sys/stat.h>
 
@@ -159,3 +160,30 @@ string trim_whitespace(const string& s)
 
 	return result;
 }
+
+string clean_filename(const string& s)
+{
+	string result = s;
+
+	set<char> illegal;
+
+	illegal.insert('/');
+    illegal.insert('\\');
+    illegal.insert('<');
+    illegal.insert('>');
+    illegal.insert(':');
+    illegal.insert('"');
+    illegal.insert('|');
+    illegal.insert('?');
+    illegal.insert('*');
+
+	for (char& c : result)
+	{
+		if (0 != illegal.count(c))
+		{
+			c = ';';
+		}
+	}
+
+	return result;
+}
diff --git a/common.h b/common.h
index 12c21db..c069907 100644
--- a/common.h
+++ b/common.h
@@ -18,5 +18,6 @@ void json_extract(const nlohmann::json& j, const std::string& key,
 void json_extract(const nlohmann::json& j, const std::string& key, bool& out);
 bool ensure_folder(const std::string& main_path, const std::string& folder);
 std::string trim_whitespace(const std::string& s);
+std::string clean_filename(const std::string& s);
 
 #endif // COMMON_H_