diff --git a/native/arithmetic.c b/native/arithmetic.c
index 907e3420eb..600e33ea21 100644
--- a/native/arithmetic.c
+++ b/native/arithmetic.c
@@ -1,7 +1,7 @@
 #include "factor.h"
 
 /* This function is called by the compiler. It returns an untagged fixnum. */
-F_FIXNUM arithmetic_type(void)
+CELL arithmetic_type(void)
 {
 	CELL obj1 = dpeek(), obj2 = get(ds - CELLS);
 	CELL type1 = TAG(obj1), type2 = TAG(obj2);
diff --git a/native/arithmetic.h b/native/arithmetic.h
index 51bb3c32ba..418547db52 100644
--- a/native/arithmetic.h
+++ b/native/arithmetic.h
@@ -1,2 +1,2 @@
-F_FIXNUM arithmetic_type(void);
+DLLEXPORT CELL arithmetic_type(void);
 void primitive_arithmetic_type(void);