diff --git a/CHANGELOG.md b/CHANGELOG.md
index efeed7a70..9911718d2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -60,6 +60,7 @@ _Breaking developer changes, which may affect downstream projects or sites that
 #### :bug: Bugfixes
 * Fix hidden tooltips on map control toolbar ([#8781])
 * Fix glitching out turn restriction minimap on narrow sidebars ([#8792])
+* Fix non-string properties of GeoJSON custom map data not being displayed correctly ([#8825], thanks [@k-yle])
 * Fix a bug which made it impossible to switch to a custom TMS imagery layer after using a custom WMS source and vice versa ([#8057])
 * Fix a bug where the validator might show wrong tagging suggestions for a preset if another preset has a partial match ([#8828], thanks [@bhousel])
 * Show correct vintage and other metadata for "Esri World Imagery"'s higher zoom levels
@@ -88,6 +89,7 @@ _Breaking developer changes, which may affect downstream projects or sites that
 [#8813]: https://github.com/openstreetmap/iD/issues/8813
 [#8817]: https://github.com/openstreetmap/iD/pull/8817
 [#8818]: https://github.com/openstreetmap/iD/issues/8818
+[#8825]: https://github.com/openstreetmap/iD/pull/8825
 [#8828]: https://github.com/openstreetmap/iD/pull/8828
 [#8831]: https://github.com/openstreetmap/iD/issues/8831
 [#8836]: https://github.com/openstreetmap/iD/issues/8836
diff --git a/modules/svg/data.js b/modules/svg/data.js
index 3ddea8c9e..a88e4b0ff 100644
--- a/modules/svg/data.js
+++ b/modules/svg/data.js
@@ -315,6 +315,21 @@ export function svgData(projection, context, dispatch) {
     }
 
 
+    function stringifyGeojsonProperties(feature) {
+        const properties = feature.properties;
+        for (const key in properties) {
+            const property = properties[key];
+            if (typeof property === 'number' || typeof property === 'boolean' || Array.isArray(property)) {
+                properties[key] = property.toString();
+            } else if (property === null) {
+                properties[key] = 'null';
+            } else if (typeof property === 'object') {
+                properties[key] = JSON.stringify(property);
+            }
+        }
+    }
+
+
     drawData.setFile = function(extension, data) {
         _template = null;
         _fileList = null;
@@ -332,6 +347,11 @@ export function svgData(projection, context, dispatch) {
             case '.geojson':
             case '.json':
                 gj = JSON.parse(data);
+                if (gj.type === 'FeatureCollection') {
+                    gj.features.forEach(stringifyGeojsonProperties);
+                } else if (gj.type === 'Feature') {
+                    stringifyGeojsonProperties(gj);
+                }
                 break;
         }
 
diff --git a/modules/ui/sections/raw_tag_editor.js b/modules/ui/sections/raw_tag_editor.js
index cc9776073..a4d558fac 100644
--- a/modules/ui/sections/raw_tag_editor.js
+++ b/modules/ui/sections/raw_tag_editor.js
@@ -11,6 +11,7 @@ import { t } from '../../core/localizer';
 import { utilArrayDifference, utilArrayIdentical } from '../../util/array';
 import { utilGetSetValue, utilNoAuto, utilRebind, utilTagDiff } from '../../util';
 
+
 export function uiSectionRawTagEditor(id, context) {
 
     var section = uiSection(id, context)
diff --git a/test/spec/svg/data.js b/test/spec/svg/data.js
index d064e1a77..6c2b70b2c 100644
--- a/test/spec/svg/data.js
+++ b/test/spec/svg/data.js
@@ -22,7 +22,11 @@ describe('iD.svgData', function () {
         '        "area": 19717.8,' +
         '        "name": "New Jersey",' +
         '        "name_en": "New Jersey",' +
-        '        "osm_id": 316973311' +
+        '        "osm_id": 316973311,' +
+        '        "flag": true,' +
+        '        "list": [1,2,3],' +
+        '        "null": null,' +
+        '        "object": {}' +
         '      },' +
         '      "id": 316973311' +
         '    }' +
@@ -171,6 +175,11 @@ describe('iD.svgData', function () {
                 path = surface.selectAll('path.stroke');
                 expect(path.nodes().length).to.eql(1);
                 expect(path.attr('d')).to.match(/^M.*z$/);
+                expect(render.geojson().features[0].properties.osm_id).to.be.a('string');
+                expect(render.geojson().features[0].properties.flag).to.be.a('string');
+                expect(render.geojson().features[0].properties.list).to.be.a('string');
+                expect(render.geojson().features[0].properties.null).to.be.a('string');
+                expect(render.geojson().features[0].properties.object).to.be.a('string');
                 done();
             }, 200);
         });