diff --git a/kernel/log.cc b/kernel/log.cc
index 34e56f8ac..7159c8e13 100644
--- a/kernel/log.cc
+++ b/kernel/log.cc
@@ -39,7 +39,7 @@
 YOSYS_NAMESPACE_BEGIN
 
 std::vector<FILE*> log_files;
-std::vector<std::ostream*> log_streams;
+std::vector<std::ostream*> log_streams, log_warning_streams;
 std::vector<std::string> log_scratchpads;
 std::map<std::string, std::set<std::string>> log_hdump;
 std::vector<std::regex> log_warn_regexes, log_nowarn_regexes, log_werror_regexes;
@@ -100,7 +100,7 @@ int gettimeofday(struct timeval *tv, struct timezone *tz)
 }
 #endif
 
-static void logv_string(std::string_view format, std::string str) {
+static void logv_string(std::string_view format, std::string str, LogSeverity severity = LogSeverity::LOG_INFO) {
 	size_t remove_leading = 0;
 	while (format.size() > 1 && format[0] == '\n') {
 		logv_string("\n", "\n");
@@ -156,6 +156,10 @@ static void logv_string(std::string_view format, std::string str) {
 
 		for (auto f : log_streams)
 			*f << time_str;
+
+		if (severity >= LogSeverity::LOG_WARNING)
+			for (auto f : log_warning_streams)
+				*f << time_str;
 	}
 
 	for (auto f : log_files)
@@ -164,6 +168,12 @@ static void logv_string(std::string_view format, std::string str) {
 	for (auto f : log_streams)
 		*f << str;
 
+	if (severity >= LogSeverity::LOG_WARNING)
+		for (auto f : log_warning_streams) {
+			*f << str;
+			f->flush();
+		}
+
 	RTLIL::Design *design = yosys_get_design();
 	if (design != nullptr)
 		for (auto &scratchpad : log_scratchpads)
@@ -201,11 +211,11 @@ static void logv_string(std::string_view format, std::string str) {
 	}
 }
 
-void log_formatted_string(std::string_view format, std::string str)
+void log_formatted_string(std::string_view format, std::string str, LogSeverity severity)
 {
 	if (log_make_debug && !ys_debug(1))
 		return;
-	logv_string(format, std::move(str));
+	logv_string(format, std::move(str), severity);
 }
 
 void log_formatted_header(RTLIL::Design *design, std::string_view format, std::string str)
@@ -291,7 +301,7 @@ void log_formatted_warning(std::string_view prefix, std::string message)
 			if (log_errfile != NULL && !log_quiet_warnings)
 				log_files.push_back(log_errfile);
 
-			log("%s%s", prefix, message);
+			log_formatted_string("%s", stringf("%s%s", prefix, message), LogSeverity::LOG_WARNING);
 			log_flush();
 
 			if (log_errfile != NULL && !log_quiet_warnings)
@@ -339,7 +349,7 @@ static void log_error_with_prefix(std::string_view prefix, std::string str)
 	}
 
 	log_last_error = std::move(str);
-	log("%s%s", prefix, log_last_error);
+	log_formatted_string("%s", stringf("%s%s", prefix, log_last_error), LogSeverity::LOG_ERROR);
 	log_flush();
 
 	log_make_debug = bak_log_make_debug;
@@ -425,7 +435,7 @@ void log_formatted_cmd_error(std::string str)
 			pop_errfile = true;
 		}
 
-		log("ERROR: %s", log_last_error);
+		log_formatted_string("ERROR: %s", log_last_error, LogSeverity::LOG_ERROR);
 		log_flush();
 
 		if (pop_errfile)
diff --git a/kernel/log.h b/kernel/log.h
index 144570026..208a39e02 100644
--- a/kernel/log.h
+++ b/kernel/log.h
@@ -94,8 +94,15 @@ YOSYS_NAMESPACE_BEGIN
 
 struct log_cmd_error_exception { };
 
+enum LogSeverity {
+	LOG_INFO,
+	LOG_WARNING,
+	LOG_ERROR
+};
+
 extern std::vector<FILE*> log_files;
 extern std::vector<std::ostream*> log_streams;
+extern std::vector<std::ostream*> log_warning_streams;
 extern std::vector<std::string> log_scratchpads;
 extern std::map<std::string, std::set<std::string>> log_hdump;
 extern std::vector<std::regex> log_warn_regexes, log_nowarn_regexes, log_werror_regexes;
@@ -132,12 +139,10 @@ static inline bool ys_debug(int = 0) { return false; }
 #endif
 #  define log_debug(...) do { if (ys_debug(1)) log(__VA_ARGS__); } while (0)
 
-void log_formatted_string(std::string_view format, std::string str);
+void log_formatted_string(std::string_view format, std::string str, LogSeverity severity = LogSeverity::LOG_INFO);
 template <typename... Args>
 inline void log(FmtString<TypeIdentity<Args>...> fmt, const Args &... args)
 {
-	if (log_make_debug && !ys_debug(1))
-		return;
 	log_formatted_string(fmt.format_string(), fmt.format(args...));
 }