diff --git a/src/directives/external-content.ts b/src/directives/external-content.ts
index fac78ee17..e70858ab0 100644
--- a/src/directives/external-content.ts
+++ b/src/directives/external-content.ts
@@ -150,7 +150,7 @@ export class CoreExternalContentDirective implements AfterViewInit, OnChanges {
         }
 
         // Avoid handling data url's.
-        if (url.indexOf('data:') === 0) {
+        if (url && url.indexOf('data:') === 0) {
             this.invalid = true;
 
             return;
diff --git a/src/directives/format-text.ts b/src/directives/format-text.ts
index 1335b31de..e8bafbbab 100644
--- a/src/directives/format-text.ts
+++ b/src/directives/format-text.ts
@@ -468,7 +468,7 @@ export class CoreFormatTextDirective implements OnChanges {
             // Wait for images to load.
             let promise: Promise<any> = null;
             if (externalImages.length) {
-                promise = Promise.all(externalImages.map((externalImage) => {
+                promise = Promise.all(externalImages.map((externalImage): any => {
                     if (externalImage.loaded) {
                         // Image has already been loaded, no need to wait.
                         return Promise.resolve();