diff --git a/modules/renderer/background.js b/modules/renderer/background.js
index a4ff533d7..44d79e638 100644
--- a/modules/renderer/background.js
+++ b/modules/renderer/background.js
@@ -271,6 +271,7 @@ export function rendererBackground(context) {
     context.history().photoOverlaysUsed(photoOverlaysUsed);
   };
 
+  let _checkedBlocklists;
 
   background.sources = (extent, zoom, includeCurrent) => {
     if (!_imageryIndex) return [];   // called before init()?
@@ -283,15 +284,19 @@ export function rendererBackground(context) {
 
     const osm = context.connection();
     const blocklists = osm && osm.imageryBlocklists();
-    const isBlocked = blocklists && function(source) {
-      return blocklists.some(function(blocklist) {
-        return new RegExp(blocklist).test(source.template());
+
+    if (blocklists && blocklists !== _checkedBlocklists) {
+      _imageryIndex.backgrounds.forEach(source => {
+        source.isBlocked = blocklists.some(function(blocklist) {
+          return blocklist.test(source.template());
+        });
       });
-    };
+      _checkedBlocklists = blocklists;
+    }
 
     return _imageryIndex.backgrounds.filter(source => {
-      if (includeCurrent && currSource === source) return true;  // optionally include the current imagery
-      if (isBlocked && isBlocked(source)) return false;          // even bundled sources may be blocked - #7905
+      if (includeCurrent && currSource === source) return true;  // optionally always include the current imagery
+      if (source.isBlocked) return false;                        // even bundled sources may be blocked - #7905
       if (!source.polygon) return true;                          // always include imagery with worldwide coverage
       if (zoom && zoom < 6) return false;                        // optionally exclude local imagery at low zooms
       return visible[source.id];                                 // include imagery visible in given extent
@@ -320,19 +325,15 @@ export function rendererBackground(context) {
     let regex;
 
     for (let i = 0; i < blocklists.length; i++) {
-      try {
-        regex = new RegExp(blocklists[i]);
-        fail = regex.test(template);
-        tested++;
-        if (fail) break;
-      } catch (e) {
-        /* noop */
-      }
+      regex = blocklists[i];
+      fail = regex.test(template);
+      tested++;
+      if (fail) break;
     }
 
     // ensure at least one test was run.
     if (!tested) {
-      regex = new RegExp('.*\.google(apis)?\..*/(vt|kh)[\?/].*([xyz]=.*){3}.*');
+      regex = /.*\.google(apis)?\..*\/(vt|kh)[\?\/].*([xyz]=.*){3}.*/;
       fail = regex.test(template);
     }
 
diff --git a/modules/services/osm.js b/modules/services/osm.js
index 8fa670cbd..d9887a5bf 100644
--- a/modules/services/osm.js
+++ b/modules/services/osm.js
@@ -24,7 +24,7 @@ var oauth = osmAuth({
     done: authDone
 });
 // hardcode default block of Google Maps
-var _imageryBlocklists = ['.*\.google(apis)?\..*/(vt|kh)[\?/].*([xyz]=.*){3}.*'];
+var _imageryBlocklists = [/.*\.google(apis)?\..*\/(vt|kh)[\?\/].*([xyz]=.*){3}.*/];
 var _tileCache = { toLoad: {}, loaded: {}, inflight: {}, seen: {}, rtree: new RBush() };
 var _noteCache = { toLoad: {}, loaded: {}, inflight: {}, inflightPost: {}, note: {}, closed: {}, rtree: new RBush() };
 var _userCache = { toLoad: {}, user: {} };
@@ -923,9 +923,14 @@ export default {
             var elements = xml.getElementsByTagName('blacklist');
             var regexes = [];
             for (var i = 0; i < elements.length; i++) {
-                var regex = elements[i].getAttribute('regex');  // needs unencode?
-                if (regex) {
-                    regexes.push(regex);
+                var regexString = elements[i].getAttribute('regex');  // needs unencode?
+                if (regexString) {
+                    try {
+                        var regex = new RegExp(regexString);
+                        regexes.push(regex);
+                    } catch (e) {
+                        /* noop */
+                    }
                 }
             }
             if (regexes.length) {
diff --git a/modules/svg/data.js b/modules/svg/data.js
index f16f8c803..42ebb35a3 100644
--- a/modules/svg/data.js
+++ b/modules/svg/data.js
@@ -388,19 +388,15 @@ export function svgData(projection, context, dispatch) {
             var regex;
 
             for (var i = 0; i < blocklists.length; i++) {
-                try {
-                    regex = new RegExp(blocklists[i]);
-                    fail = regex.test(val);
-                    tested++;
-                    if (fail) break;
-                } catch (e) {
-                    /* noop */
-                }
+                regex = blocklists[i];
+                fail = regex.test(val);
+                tested++;
+                if (fail) break;
             }
 
             // ensure at least one test was run.
             if (!tested) {
-                regex = new RegExp('.*\.google(apis)?\..*/(vt|kh)[\?/].*([xyz]=.*){3}.*');
+                regex = /.*\.google(apis)?\..*\/(vt|kh)[\?\/].*([xyz]=.*){3}.*/;
                 fail = regex.test(val);
             }
         }
diff --git a/test/spec/services/osm.js b/test/spec/services/osm.js
index 8e73b66e2..3619e3270 100644
--- a/test/spec/services/osm.js
+++ b/test/spec/services/osm.js
@@ -732,7 +732,7 @@ describe('iD.serviceOsm', function () {
             it('updates imagery blocklists', function(done) {
                 connection.status(function() {
                     var blocklists = connection.imageryBlocklists();
-                    expect(blocklists).to.deep.equal(['\.foo\.com','\.bar\.org']);
+                    expect(blocklists).to.deep.equal([new RegExp('\.foo\.com'), new RegExp('\.bar\.org')]);
                     done();
                 });