diff --git a/src/prim/unix/prim.c b/src/prim/unix/prim.c
index 314281fe..605a684e 100644
--- a/src/prim/unix/prim.c
+++ b/src/prim/unix/prim.c
@@ -55,6 +55,10 @@ terms of the MIT license. A copy of the license can be found in the file
   #include <sys/syscall.h>
 #endif
 
+#if defined(__HAIKU__)
+#include <fcntl.h>
+#endif
+
 //------------------------------------------------------------------------------------
 // Use syscalls for some primitives to allow for libraries that override open/read/close etc.
 // and do allocation themselves; using syscalls prevents recursion when mimalloc is