diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index bfb177e9b26..2650042ff85 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -2520,8 +2520,8 @@ std::string RTLIL::Module::rtlil_dump() {
 }
 
 // Returns a hash of the RTLIL dump
-std::string RTLIL::Module::rtlil_hash() {
-	return std::to_string(hash_ops<std::string>::hash(rtlil_dump()));
+unsigned int RTLIL::Module::rtlil_hash() {
+	return hash_ops<std::string>::hash(rtlil_dump());
 }
 
 void RTLIL::Module::swap_names(RTLIL::Cell *c1, RTLIL::Cell *c2)
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index bd9d318792d..350a6afe36c 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1592,7 +1592,7 @@ struct RTLIL::Module : public RTLIL::AttrObject
 	RTLIL::SigSpec FutureFF        (RTLIL::IdString name, const RTLIL::SigSpec &sig_e, const std::string &src = "");
 
 	std::string rtlil_dump();
-	std::string rtlil_hash();
+	unsigned int rtlil_hash();
 
 #ifdef WITH_PYTHON
 	static std::map<unsigned int, RTLIL::Module*> *get_all_modules(void);