diff --git a/common/common.c b/common/common.c
index 6607f95c3c..79f135a516 100644
--- a/common/common.c
+++ b/common/common.c
@@ -120,7 +120,7 @@ bool mp_rect_intersection(struct mp_rect *rc, const struct mp_rect *rc2)
     return rc->x1 > rc->x0 && rc->y1 > rc->y0;
 }
 
-bool mp_rect_equals(struct mp_rect *rc1, struct mp_rect *rc2)
+bool mp_rect_equals(const struct mp_rect *rc1, const struct mp_rect *rc2)
 {
     return rc1->x0 == rc2->x0 && rc1->y0 == rc2->y0 &&
            rc1->x1 == rc2->x1 && rc1->y1 == rc2->y1;
diff --git a/common/common.h b/common/common.h
index 206062e8ed..93a8ded918 100644
--- a/common/common.h
+++ b/common/common.h
@@ -106,7 +106,7 @@ struct mp_rect {
 void mp_rect_union(struct mp_rect *rc, const struct mp_rect *src);
 bool mp_rect_intersection(struct mp_rect *rc, const struct mp_rect *rc2);
 bool mp_rect_contains(struct mp_rect *rc, int x, int y);
-bool mp_rect_equals(struct mp_rect *rc1, struct mp_rect *rc2);
+bool mp_rect_equals(const struct mp_rect *rc1, const struct mp_rect *rc2);
 int mp_rect_subtract(const struct mp_rect *rc1, const struct mp_rect *rc2,
                      struct mp_rect res_array[4]);