diff --git a/src/whereami.c b/src/whereami.c
index 78f02c39..392d1fa5 100644
--- a/src/whereami.c
+++ b/src/whereami.c
@@ -83,7 +83,9 @@ extern "C" {
 #if (_MSC_VER >= 1900)
 #include <stdbool.h>
 #else
+#ifndef bool
 #define bool int
+#endif
 #define false 0
 #define true 1
 #endif