diff --git a/src/wikisort/libwikisort.c b/src/wikisort/libwikisort.c
index 6427ec1b..8817f9fa 100644
--- a/src/wikisort/libwikisort.c
+++ b/src/wikisort/libwikisort.c
@@ -30,11 +30,13 @@
 #include <limits.h>
 
 /* various #defines for the C code */
+#if __STDC_VERSION__ <= 201710L
 #ifndef true
 #define true 1
 #define false 0
 typedef uint8_t bool;
 #endif
+#endif
 
 #define Var(name, value, type) type name = value