diff --git a/src/js/1p-filters.js b/src/js/1p-filters.js
index e1cee3bda..9c756fdc8 100644
--- a/src/js/1p-filters.js
+++ b/src/js/1p-filters.js
@@ -1,7 +1,7 @@
 /*******************************************************************************
 
     uBlock Origin - a browser extension to block requests.
-    Copyright (C) 2014-2018 Raymond Hill
+    Copyright (C) 2014-present Raymond Hill
 
     This program is free software: you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -117,9 +117,8 @@ const handleImportFilePicker = function() {
         let matches = reAbpSubscriptionExtractor.exec(s);
         // Not an ABP backup file
         if ( matches === null ) { return s; }
-        // 
         const out = [];
-        while ( matches !== null ) {
+        do {
             if ( matches.length === 2 ) {
                 let filterMatch = reAbpFilterExtractor.exec(matches[1].trim());
                 if ( filterMatch !== null && filterMatch.length === 2 ) {
@@ -127,13 +126,22 @@ const handleImportFilePicker = function() {
                 }
             }
             matches = reAbpSubscriptionExtractor.exec(s);
-        }
+        } while ( matches !== null );
         return out.join('\n');
     };
 
     const fileReaderOnLoadHandler = function() {
-        const sanitized = abpImporter(this.result);
-        cmEditor.setValue(cmEditor.getValue().trim() + '\n' + sanitized);
+        let content = abpImporter(this.result);
+        content = uBlockDashboard.mergeNewLines(
+            cmEditor.getValue().trim(),
+            content
+        );
+        cmEditor.operation(( ) => {
+            const cmPos = cmEditor.getCursor();
+            cmEditor.setValue(`${content}\n`);
+            cmEditor.setCursor(cmPos);
+            cmEditor.focus();
+        });
     };
     const file = this.files[0];
     if ( file === undefined || file.name === '' ) { return; }
diff --git a/src/js/dashboard-common.js b/src/js/dashboard-common.js
index 14ad39d51..b97579bf4 100644
--- a/src/js/dashboard-common.js
+++ b/src/js/dashboard-common.js
@@ -34,7 +34,7 @@ self.uBlockDashboard = self.uBlockDashboard || {};
 
 self.uBlockDashboard.mergeNewLines = function(text, newText) {
     // Step 1: build dictionary for existing lines.
-    const fromDict = Object.create(null);
+    const fromDict = new Map();
     let lineBeg = 0;
     let textEnd = text.length;
     while ( lineBeg < textEnd ) {
@@ -45,17 +45,15 @@ self.uBlockDashboard.mergeNewLines = function(text, newText) {
                 lineEnd = textEnd;
             }
         }
-        let line = text.slice(lineBeg, lineEnd).trim();
+        const line = text.slice(lineBeg, lineEnd).trim();
         lineBeg = lineEnd + 1;
-        if ( line.length === 0 ) {
-            continue;
-        }
+        if ( line.length === 0 ) { continue; }
         const hash = line.slice(0, 8);
-        const bucket = fromDict[hash];
+        const bucket = fromDict.get(hash);
         if ( bucket === undefined ) {
-            fromDict[hash] = line;
+            fromDict.set(hash, line);
         } else if ( typeof bucket === 'string' ) {
-            fromDict[hash] = [bucket, line];
+            fromDict.set(hash, [ bucket, line ]);
         } else /* if ( Array.isArray(bucket) ) */ {
             bucket.push(line);
         }
@@ -73,7 +71,7 @@ self.uBlockDashboard.mergeNewLines = function(text, newText) {
                 lineEnd = textEnd;
             }
         }
-        let line = newText.slice(lineBeg, lineEnd).trim();
+        const line = newText.slice(lineBeg, lineEnd).trim();
         lineBeg = lineEnd + 1;
         if ( line.length === 0 ) {
             if ( out[out.length - 1] !== '' ) {
@@ -81,7 +79,7 @@ self.uBlockDashboard.mergeNewLines = function(text, newText) {
             }
             continue;
         }
-        const bucket = fromDict[line.slice(0, 8)];
+        const bucket = fromDict.get(line.slice(0, 8));
         if ( bucket === undefined ) {
             out.push(line);
             continue;
@@ -96,7 +94,11 @@ self.uBlockDashboard.mergeNewLines = function(text, newText) {
         }
     }
 
-    return text.trim() + '\n' + out.join('\n');
+    const append = out.join('\n').trim();
+    if ( text !== '' && append !== '' ) {
+        text += '\n\n';
+    }
+    return text + append;
 };
 
 /******************************************************************************/