diff --git a/lib/badge-data.js b/lib/badge-data.js
index 31ca18c93f..706554abea 100644
--- a/lib/badge-data.js
+++ b/lib/badge-data.js
@@ -20,7 +20,11 @@ function isDataUri(s) {
 function prependPrefix(s, prefix) {
   if (s === undefined) {
     return undefined;
-  } else if (s.startsWith(prefix)) {
+  }
+
+  s = '' + s;
+
+  if (s.startsWith(prefix)) {
     return s;
   } else {
     return prefix + s;
@@ -59,8 +63,10 @@ function makeLabel(defaultLabel, overrides) {
 }
 
 function makeLogo(defaultNamedLogo, overrides) {
-  const maybeDataUri = prependPrefix(overrides.logo, 'data:');
-  const maybeNamedLogo = overrides.logo === undefined ? defaultNamedLogo : overrides.logo;
+  const logo = 'logo' in overrides ? '' + overrides.logo : undefined;
+
+  const maybeDataUri = prependPrefix(logo, 'data:');
+  const maybeNamedLogo = logo === undefined ? defaultNamedLogo : logo;
 
   if (isDataUri(maybeDataUri)) {
     return maybeDataUri;
diff --git a/server.spec.js b/server.spec.js
index 0bea7d6714..3891ab20dd 100644
--- a/server.spec.js
+++ b/server.spec.js
@@ -43,6 +43,19 @@ describe('The server', function () {
       });
   });
 
+  // https://github.com/badges/shields/pull/1319
+  it('should not crash with a numeric logo', function () {
+    return fetch(`${baseUri}/:fruit-apple-green.svg?logo=1`)
+      .then(res => {
+        assert.ok(res.ok);
+        return res.buffer();
+      }).then(text => {
+        assert.ok(isSvg(text));
+        assert(text.includes('fruit'), 'fruit');
+        assert(text.includes('apple'), 'apple');
+      });
+  });
+
   context('with svg2img error', function () {
     const expectedError = fs.readFileSync(path.resolve(__dirname, 'public', '500.html'));