diff --git a/src/syncterm/syncterm.c b/src/syncterm/syncterm.c
index c7c730b75ea1a64451601a0b0d71856f5bd631d7..8c087c3b07d3c76db9e32fcbcf4943408e1ca49b 100644
--- a/src/syncterm/syncterm.c
+++ b/src/syncterm/syncterm.c
@@ -61,11 +61,15 @@ static const KNOWNFOLDERID FOLDERID_ProgramData = {
 #if !(defined __BORLANDC__ || defined _MSC_VER)
  #include <stdbool.h>
 #else
+#ifndef bool
  #define bool int
+#endif
+#if !(defined false && defined true)
 enum {
 	false,
 	true
 };
+#endif
 
 #endif