diff --git a/core/dive.h b/core/dive.h
index 8e9185daa..c9369885a 100644
--- a/core/dive.h
+++ b/core/dive.h
@@ -396,8 +396,6 @@ extern const char *existing_filename;
 extern void subsurface_command_line_init(int *, char ***);
 extern void subsurface_command_line_exit(int *, char ***);
 
-#define FRACTION(n, x) ((unsigned)(n) / (x)), ((unsigned)(n) % (x))
-
 extern bool is_dc_planner(const struct divecomputer *dc);
 extern bool has_planned(const struct dive *dive, bool planned);
 
diff --git a/core/membuffer.c b/core/membuffer.c
index 8efb04c9e..d0e5160ef 100644
--- a/core/membuffer.c
+++ b/core/membuffer.c
@@ -9,7 +9,7 @@
 #include <string.h>
 #include <stdio.h>
 
-#include "dive.h"
+#include "units.h"
 #include "membuffer.h"
 
 /* Only for internal use */
diff --git a/core/units.h b/core/units.h
index 8839dde1d..4232e24a3 100644
--- a/core/units.h
+++ b/core/units.h
@@ -13,6 +13,8 @@ extern "C" {
 #include <stdbool.h>
 #endif
 
+#define FRACTION(n, x) ((unsigned)(n) / (x)), ((unsigned)(n) % (x))
+
 #define O2_IN_AIR 209 // permille
 #define N2_IN_AIR 781
 #define O2_DENSITY 1331 // mg/Liter