diff --git a/include/wlr/util/transform.h b/include/wlr/util/transform.h
index d0ec5f53..6195e6d0 100644
--- a/include/wlr/util/transform.h
+++ b/include/wlr/util/transform.h
@@ -25,4 +25,9 @@ enum wl_output_transform wlr_output_transform_invert(
 enum wl_output_transform wlr_output_transform_compose(
 	enum wl_output_transform tr_a, enum wl_output_transform tr_b);
 
+/**
+ * Applies a transform to coordinates.
+ */
+void wlr_output_transform_coords(enum wl_output_transform tr, int *x, int *y);
+
 #endif
diff --git a/types/scene/surface.c b/types/scene/surface.c
index 4741dd6c..1a2b31af 100644
--- a/types/scene/surface.c
+++ b/types/scene/surface.c
@@ -130,12 +130,7 @@ static void surface_reconfigure(struct wlr_scene_surface *scene_surface) {
 
 		wlr_fbox_transform(&src_box, &src_box, state->transform,
 			buffer_width, buffer_height);
-
-		if (state->transform & WL_OUTPUT_TRANSFORM_90) {
-			int tmp = buffer_width;
-			buffer_width = buffer_height;
-			buffer_height = tmp;
-		}
+		wlr_output_transform_coords(state->transform, &buffer_width, &buffer_height);
 
 		src_box.x += (double)(clip->x * buffer_width) / state->width;
 		src_box.y += (double)(clip->y * buffer_height) / state->height;
diff --git a/types/scene/wlr_scene.c b/types/scene/wlr_scene.c
index d8c7b841..f83f7274 100644
--- a/types/scene/wlr_scene.c
+++ b/types/scene/wlr_scene.c
@@ -879,13 +879,9 @@ static void scene_node_get_size(struct wlr_scene_node *node,
 			*width = scene_buffer->dst_width;
 			*height = scene_buffer->dst_height;
 		} else if (scene_buffer->buffer) {
-			if (scene_buffer->transform & WL_OUTPUT_TRANSFORM_90) {
-				*height = scene_buffer->buffer->width;
-				*width = scene_buffer->buffer->height;
-			} else {
-				*width = scene_buffer->buffer->width;
-				*height = scene_buffer->buffer->height;
-			}
+			*width = scene_buffer->buffer->width;
+			*height = scene_buffer->buffer->height;
+			wlr_output_transform_coords(scene_buffer->transform, width, height);
 		}
 		break;
 	}
@@ -1544,14 +1540,13 @@ static bool scene_entry_try_direct_scanout(struct render_list_entry *entry,
 
 	struct wlr_scene_buffer *buffer = wlr_scene_buffer_from_node(node);
 
-	struct wlr_fbox default_box = {0};
-	if (buffer->transform & WL_OUTPUT_TRANSFORM_90) {
-		default_box.width = buffer->buffer->height;
-		default_box.height = buffer->buffer->width;
-	} else {
-		default_box.width = buffer->buffer->width;
-		default_box.height = buffer->buffer->height;
-	}
+	int default_width = buffer->buffer->width;
+	int default_height = buffer->buffer->height;
+	wlr_output_transform_coords(buffer->transform, &default_width, &default_height);
+	struct wlr_fbox default_box = {
+		.width = default_width,
+		.height = default_height,
+	};
 
 	if (!wlr_fbox_empty(&buffer->src_box) &&
 			!wlr_fbox_equal(&buffer->src_box, &default_box)) {
@@ -1679,11 +1674,8 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 		render_data.scale = state->scale;
 	}
 
-	if (render_data.transform & WL_OUTPUT_TRANSFORM_90) {
-		int tmp = render_data.trans_width;
-		render_data.trans_width = render_data.trans_height;
-		render_data.trans_height = tmp;
-	}
+	wlr_output_transform_coords(render_data.transform,
+		&render_data.trans_width, &render_data.trans_height);
 
 	render_data.logical.width = render_data.trans_width / render_data.scale;
 	render_data.logical.height = render_data.trans_height / render_data.scale;
diff --git a/types/wlr_compositor.c b/types/wlr_compositor.c
index 755d3760..ef05f8bb 100644
--- a/types/wlr_compositor.c
+++ b/types/wlr_compositor.c
@@ -146,16 +146,10 @@ static void surface_handle_set_input_region(struct wl_client *client,
 }
 
 static void surface_state_transformed_buffer_size(struct wlr_surface_state *state,
-		int *out_width, int *out_height) {
-	int width = state->buffer_width;
-	int height = state->buffer_height;
-	if ((state->transform & WL_OUTPUT_TRANSFORM_90) != 0) {
-		int tmp = width;
-		width = height;
-		height = tmp;
-	}
-	*out_width = width;
-	*out_height = height;
+		int *width, int *height) {
+	*width = state->buffer_width;
+	*height = state->buffer_height;
+	wlr_output_transform_coords(state->transform, width, height);
 }
 
 /**
diff --git a/util/transform.c b/util/transform.c
index 4cc725fd..de3f8ef4 100644
--- a/util/transform.c
+++ b/util/transform.c
@@ -23,3 +23,11 @@ enum wl_output_transform wlr_output_transform_compose(
 	}
 	return flipped | rotated;
 }
+
+void wlr_output_transform_coords(enum wl_output_transform tr, int *x, int *y) {
+	if (tr & WL_OUTPUT_TRANSFORM_90) {
+		int tmp = *x;
+		*x = *y;
+		*y = tmp;
+	}
+}