diff --git a/js/pmtiles.js b/js/pmtiles.js
index 86b9517..49ee68d 100644
--- a/js/pmtiles.js
+++ b/js/pmtiles.js
@@ -62,32 +62,24 @@
             this.outstanding_requests = new Map()
         }
 
-        getLeaf = tilestr => {
+        getLeaf = (offset, len) => {
             return new Promise((resolve,reject) => {
-                if (this.leaves.has(tilestr)) {
-                    resolve(this.leaves.get(tilestr))
-                } else if (this.outstanding_requests.has(tilestr)) {
-                    this.outstanding_requests.get(tilestr).push(resolve)
+                if (this.leaves.has(offset)) {
+                    resolve(this.leaves.get(offset))
+                } else if (this.outstanding_requests.has(offset)) {
+                    this.outstanding_requests.get(offset).push(resolve)
                 } else {
-                    this.outstanding_requests.set(tilestr,[])
-                    this.rootdir.then(rootdir => {
-                        if (rootdir.has(tilestr)) {
-                            var val = rootdir.get(tilestr)
-                            if (val[2] == 1) { // it is a directory
-                                fetch(this.url, {headers:{'range':'bytes=' + val[0] + '-' + (val[0] + val[1]-1)}}).then(resp => {
-                                    return resp.arrayBuffer()
-                                }).then(buf => {
-                                    var map = bytesToMap(new DataView(buf),val[1]/17)
-                                    this.leaves.set(tilestr,map)
-                                    resolve(map)
-                                    this.outstanding_requests.get(tilestr).forEach(f => {
-                                        f(map)
-                                    })
-                                    // TODO fix duplication of multiple leaves in same directory
-                                    console.log("leaves: ", this.leaves.size)
-                                })
-                            }
-                        }
+                    this.outstanding_requests.set(offset,[])
+                    fetch(this.url, {headers:{'range':'bytes=' + offset + '-' + (offset + len-1)}}).then(resp => {
+                        return resp.arrayBuffer()
+                    }).then(buf => {
+                        var map = bytesToMap(new DataView(buf),len/17)
+                        this.leaves.set(offset,map)
+                        resolve(map)
+                        this.outstanding_requests.get(offset).forEach(f => {
+                            f(map)
+                        })
+                        console.log("leaves: ", this.leaves.size)
                     })
                 }
             })
@@ -103,12 +95,15 @@
                         var z7_tile_diff = (z - 7)
                         var z7_tile = [7,Math.trunc(x / (1 << z7_tile_diff)), Math.trunc(y / (1 << z7_tile_diff))]
                         var z7_tile_str = z7_tile[0] + "_" + z7_tile[1] + "_" + z7_tile[2]
-                        return this.getLeaf(z7_tile_str).then(leafdir => {
-                            if (leafdir.has(strid)) {
-                                return leafdir.get(strid)
-                            }
-                            return null
-                        })
+                        if (rootdir.has(z7_tile_str)) {
+                            const val = rootdir.get(z7_tile_str)
+                            return this.getLeaf(val[0],val[1]).then(leafdir => {
+                                if (leafdir.has(strid)) {
+                                    return leafdir.get(strid)
+                                }
+                                return null
+                            })
+                        }
                    } 
                 }
                 return null