diff --git a/core/membuffer.c b/core/membuffer.c
index 71832a428..548b70d45 100644
--- a/core/membuffer.c
+++ b/core/membuffer.c
@@ -218,7 +218,7 @@ void put_degrees(struct membuffer *b, degrees_t value, const char *pre, const ch
 	put_format(b, "%s%s%u.%06u%s", pre, sign, FRACTION(udeg, 1000000), post);
 }
 
-void put_location(struct membuffer *b, location_t *loc, const char *pre, const char *post)
+void put_location(struct membuffer *b, const location_t *loc, const char *pre, const char *post)
 {
 	if (has_location(loc)) {
 		put_degrees(b, loc->lat, pre, " ");
diff --git a/core/membuffer.h b/core/membuffer.h
index a5f7d023d..03c42a61d 100644
--- a/core/membuffer.h
+++ b/core/membuffer.h
@@ -111,7 +111,7 @@ extern void put_duration(struct membuffer *, duration_t, const char *, const cha
 extern void put_pressure(struct membuffer *, pressure_t, const char *, const char *);
 extern void put_salinity(struct membuffer *, int, const char *, const char *);
 extern void put_degrees(struct membuffer *b, degrees_t value, const char *, const char *);
-extern void put_location(struct membuffer *b, location_t *, const char *, const char *);
+extern void put_location(struct membuffer *b, const location_t *, const char *, const char *);
 
 #ifdef __cplusplus
 }