diff --git a/src/bitutils.c b/src/bitutils.c
index 3025d7c..f11734b 100644
--- a/src/bitutils.c
+++ b/src/bitutils.c
@@ -1,8 +1,13 @@
 #include "postgres.h"
 
 #include "bitutils.h"
+#include "halfvec.h"			/* for USE_DISPATCH and USE_TARGET_CLONES */
 #include "port/pg_bitutils.h"
 
+#if defined(USE_DISPATCH)
+#define BIT_DISPATCH
+#endif
+
 #ifdef BIT_DISPATCH
 #include <immintrin.h>
 
diff --git a/src/bitutils.h b/src/bitutils.h
index db362e1..b834190 100644
--- a/src/bitutils.h
+++ b/src/bitutils.h
@@ -8,12 +8,6 @@
 #error "Requires PostgreSQL 12+"
 #endif
 
-#include "halfvec.h"			/* for USE_DISPATCH and USE_TARGET_CLONES */
-
-#if defined(USE_DISPATCH)
-#define BIT_DISPATCH
-#endif
-
 extern uint64 (*BitHammingDistance) (uint32 bytes, unsigned char *ax, unsigned char *bx, uint64 distance);
 extern double (*BitJaccardDistance) (uint32 bytes, unsigned char *ax, unsigned char *bx, uint64 ab, uint64 aa, uint64 bb);