diff --git a/include/PR/os_libc.h b/include/PR/os_libc.h
index 9eb872e7..05ab6682 100644
--- a/include/PR/os_libc.h
+++ b/include/PR/os_libc.h
@@ -5,7 +5,7 @@
 
 // old bstring functions that aren't present on some platforms
 
-#if defined(__APPLE__)
+#if defined(__APPLE__) || defined(__HAIKU__)
 
 // macOS libc has them
 #include <strings.h>