diff --git a/bacnet-stack/ports/pic18/stdbool.h b/bacnet-stack/ports/pic18/stdbool.h
index 2b7511a6..696ffd85 100644
--- a/bacnet-stack/ports/pic18/stdbool.h
+++ b/bacnet-stack/ports/pic18/stdbool.h
@@ -4,7 +4,7 @@
 /* C99 Boolean types for compilers without C99 support */
 
 #ifndef __cplusplus
-typedef int _Bool;
+typedef char _Bool;
 #ifndef bool
 #define bool _Bool
 #endif