diff --git a/libs/plugins/reasonablesynth.lv2/rsynth.c b/libs/plugins/reasonablesynth.lv2/rsynth.c
index 061d72dbff..a6c74aa26c 100644
--- a/libs/plugins/reasonablesynth.lv2/rsynth.c
+++ b/libs/plugins/reasonablesynth.lv2/rsynth.c
@@ -25,6 +25,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdint.h>
+#include <stdbool.h>
 #include <assert.h>
 
 #ifndef BUFFER_SIZE_SAMPLES