diff --git a/kernel/log.cc b/kernel/log.cc
index 679a55562..b4c35d25a 100644
--- a/kernel/log.cc
+++ b/kernel/log.cc
@@ -101,7 +101,7 @@ int gettimeofday(struct timeval *tv, struct timezone *tz)
 }
 #endif
 
-void logv(const char *format, va_list ap)
+static void logv(const char *format, va_list ap)
 {
 	while (format[0] == '\n' && format[1] != 0) {
 		log("\n");
@@ -203,7 +203,7 @@ void logv(const char *format, va_list ap)
 	}
 }
 
-void logv_header(RTLIL::Design *design, const char *format, va_list ap)
+static void logv_header(RTLIL::Design *design, const char *format, va_list ap)
 {
 	bool pop_errfile = false;
 
@@ -298,12 +298,12 @@ static void logv_warning_with_prefix(const char *prefix,
 	}
 }
 
-void logv_warning(const char *format, va_list ap)
+static void logv_warning(const char *format, va_list ap)
 {
 	logv_warning_with_prefix("Warning: ", format, ap);
 }
 
-void logv_warning_noprefix(const char *format, va_list ap)
+static void logv_warning_noprefix(const char *format, va_list ap)
 {
 	logv_warning_with_prefix("", format, ap);
 }
@@ -379,7 +379,8 @@ static void logv_error_with_prefix(const char *prefix,
 #endif
 }
 
-void logv_error(const char *format, va_list ap)
+[[noreturn]]
+static void logv_error(const char *format, va_list ap)
 {
 	logv_error_with_prefix("ERROR: ", format, ap);
 }
diff --git a/kernel/log.h b/kernel/log.h
index e26ef072c..b6451bcac 100644
--- a/kernel/log.h
+++ b/kernel/log.h
@@ -119,11 +119,6 @@ extern int log_make_debug;
 extern int log_force_debug;
 extern int log_debug_suppressed;
 
-void logv(const char *format, va_list ap);
-void logv_header(RTLIL::Design *design, const char *format, va_list ap);
-void logv_warning(const char *format, va_list ap);
-void logv_warning_noprefix(const char *format, va_list ap);
-[[noreturn]] void logv_error(const char *format, va_list ap);
 [[noreturn]] void logv_file_error(const string &filename, int lineno, const char *format, va_list ap);
 
 void log(const char *format, ...)  YS_ATTRIBUTE(format(printf, 1, 2));