diff --git a/convert_osm/src/osm_reader.rs b/convert_osm/src/osm_reader.rs
index 587d3c99d3..e404dbab87 100644
--- a/convert_osm/src/osm_reader.rs
+++ b/convert_osm/src/osm_reader.rs
@@ -4,8 +4,6 @@ use map_model::raw::{OriginalBuilding, RawArea, RawBuilding, RawMap, RawRoad, Re
 use map_model::{osm, AreaType};
 use osm_xml;
 use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
-use std::fs::File;
-use std::io::{BufRead, BufReader};
 
 pub fn extract_osm(
     osm_path: &str,
@@ -38,8 +36,17 @@ pub fn extract_osm(
     );
     done(timer);
 
-    let mut map = if let Some(ref path) = maybe_clip_path {
-        read_osmosis_polygon(path, city_name, map_name)
+    let mut map = if let Some(path) = maybe_clip_path {
+        let pts = LonLat::read_osmosis_polygon(path.to_string()).unwrap();
+        let mut gps_bounds = GPSBounds::new();
+        for pt in &pts {
+            gps_bounds.update(*pt);
+        }
+
+        let mut map = RawMap::blank(city_name, map_name);
+        map.boundary_polygon = Polygon::new(&gps_bounds.must_convert(&pts));
+        map.gps_bounds = gps_bounds;
+        map
     } else {
         let mut m = RawMap::blank(city_name, map_name);
         for node in doc.nodes.values() {
@@ -558,33 +565,3 @@ fn glue_to_boundary(result_pl: PolyLine, boundary: &Ring) -> Option<Polygon> {
     assert_eq!(trimmed_pts[0], *trimmed_pts.last().unwrap());
     Some(Polygon::new(&trimmed_pts))
 }
-
-fn read_osmosis_polygon(path: &str, city_name: &str, map_name: &str) -> RawMap {
-    let mut pts: Vec<LonLat> = Vec::new();
-    let mut gps_bounds = GPSBounds::new();
-    for (idx, maybe_line) in BufReader::new(File::open(path).unwrap())
-        .lines()
-        .enumerate()
-    {
-        if idx == 0 || idx == 1 {
-            continue;
-        }
-        let line = maybe_line.unwrap();
-        if line == "END" {
-            break;
-        }
-        let parts: Vec<&str> = line.trim_start().split("    ").collect();
-        assert!(parts.len() == 2);
-        let pt = LonLat::new(
-            parts[0].parse::<f64>().unwrap(),
-            parts[1].parse::<f64>().unwrap(),
-        );
-        pts.push(pt);
-        gps_bounds.update(pt);
-    }
-
-    let mut map = RawMap::blank(city_name, map_name);
-    map.boundary_polygon = Polygon::new(&gps_bounds.must_convert(&pts));
-    map.gps_bounds = gps_bounds;
-    map
-}
diff --git a/game/src/devtools/mod.rs b/game/src/devtools/mod.rs
index 4ec353c3a5..2518b717b9 100644
--- a/game/src/devtools/mod.rs
+++ b/game/src/devtools/mod.rs
@@ -13,6 +13,7 @@ use ezgui::{
     hotkey, Btn, Choice, Composite, EventCtx, GfxCtx, HorizontalAlignment, Key, Line, Outcome,
     TextExt, VerticalAlignment, Widget, Wizard,
 };
+use geom::LonLat;
 
 pub struct DevToolsMode {
     composite: Composite,
@@ -119,7 +120,7 @@ fn choose_polygon(wiz: &mut Wizard, ctx: &mut EventCtx, app: &mut App) -> Option
     let name = wiz.wrap(ctx).choose_string("Edit which polygon?", || {
         abstutil::list_all_objects("../data/input/seattle/polygons/".to_string())
     })?;
-    match polygon::read_from_osmosis(format!("../data/input/seattle/polygons/{}.poly", name)) {
+    match LonLat::read_osmosis_polygon(format!("../data/input/seattle/polygons/{}.poly", name)) {
         Ok(pts) => Some(Transition::Replace(polygon::PolygonEditor::new(
             ctx, app, name, pts,
         ))),
diff --git a/game/src/devtools/polygon.rs b/game/src/devtools/polygon.rs
index 6cf0beb927..89291a5e38 100644
--- a/game/src/devtools/polygon.rs
+++ b/game/src/devtools/polygon.rs
@@ -5,7 +5,7 @@ use crate::managed::WrappedComposite;
 use ezgui::{hotkey, Color, Composite, EventCtx, GfxCtx, Key, Line, Outcome, Text};
 use geom::{Circle, Distance, LonLat, Polygon, Pt2D};
 use std::fs::File;
-use std::io::{BufRead, BufReader, Error, ErrorKind, Write};
+use std::io::{Error, Write};
 
 const POINT_RADIUS: Distance = Distance::const_meters(10.0);
 // Localized and internal, so don't put in ColorScheme.
@@ -165,28 +165,3 @@ fn save_as_osmosis(name: &str, pts: &Vec<LonLat>) -> Result<(), Error> {
     println!("Exported {}", path);
     Ok(())
 }
-
-pub fn read_from_osmosis(path: String) -> Result<Vec<LonLat>, Error> {
-    let f = File::open(&path)?;
-    let mut pts = Vec::new();
-    for (idx, line) in BufReader::new(f).lines().enumerate() {
-        if idx < 2 {
-            continue;
-        }
-        let line = line?;
-        if line == "END" {
-            break;
-        }
-        let parts = line.trim().split("    ").collect::<Vec<_>>();
-        pts.push(LonLat::new(
-            parts[0]
-                .parse::<f64>()
-                .map_err(|err| Error::new(ErrorKind::Other, err))?,
-            parts[1]
-                .parse::<f64>()
-                .map_err(|err| Error::new(ErrorKind::Other, err))?,
-        ));
-    }
-    pts.pop();
-    Ok(pts)
-}
diff --git a/geom/src/gps.rs b/geom/src/gps.rs
index 6f2798ce7c..40717b6ede 100644
--- a/geom/src/gps.rs
+++ b/geom/src/gps.rs
@@ -2,6 +2,8 @@ use crate::Distance;
 use ordered_float::NotNan;
 use serde_derive::{Deserialize, Serialize};
 use std::fmt;
+use std::fs::File;
+use std::io::{BufRead, BufReader, Error, ErrorKind};
 
 // longitude is x, latitude is y
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug, Serialize, Deserialize)]
@@ -52,6 +54,31 @@ impl LonLat {
         let epsilon = 1e-8;
         (self.x() - other.x()).abs() < epsilon && (self.y() - other.y()).abs() < epsilon
     }
+
+    pub fn read_osmosis_polygon(path: String) -> Result<Vec<LonLat>, Error> {
+        let f = File::open(&path)?;
+        let mut pts = Vec::new();
+        for (idx, line) in BufReader::new(f).lines().enumerate() {
+            if idx < 2 {
+                continue;
+            }
+            let line = line?;
+            if line == "END" {
+                break;
+            }
+            let parts = line.trim().split("    ").collect::<Vec<_>>();
+            pts.push(LonLat::new(
+                parts[0]
+                    .parse::<f64>()
+                    .map_err(|err| Error::new(ErrorKind::Other, err))?,
+                parts[1]
+                    .parse::<f64>()
+                    .map_err(|err| Error::new(ErrorKind::Other, err))?,
+            ));
+        }
+        pts.pop();
+        Ok(pts)
+    }
 }
 
 impl fmt::Display for LonLat {