diff --git a/lib/src/markdown.service.spec.ts b/lib/src/markdown.service.spec.ts
index 7f368121..133da0b3 100644
--- a/lib/src/markdown.service.spec.ts
+++ b/lib/src/markdown.service.spec.ts
@@ -71,16 +71,19 @@ describe('MarkdowService', () => {
     it('should return line with indent correctly', () => {
 
       const mockRaw =  [
-        '* list',       // find first line with non-whitespaces to set offset
-        '  * sub-list', // keep indent while removing from previous row offset
-        '',             // keep blank line
-        'Lorem Ipsum',  // keep everthing else
+        '   ',              // first line with only whitespaces should not determine indent offset
+        '  * list',         // find first line with non-whitespaces to set offset
+        '    * sub-list',   // keep indent while removing from previous row offset
+        '  ',               // keep blank line
+        ' Negative indent', // keep line with negative offset according to first non-whitespaces line indent
+        '  Lorem Ipsum',    // keep indent like equals to first non-whitespaces line ident
       ].join('\n');
 
       const expected = [
         '* list',
         '  * sub-list',
         '',
+        'Negative indent',
         'Lorem Ipsum',
       ].join('\n');
 
diff --git a/lib/src/markdown.service.ts b/lib/src/markdown.service.ts
index ae790819..2bb49c75 100644
--- a/lib/src/markdown.service.ts
+++ b/lib/src/markdown.service.ts
@@ -77,14 +77,23 @@ export class MarkdownService {
     return markdown
       .split('\n')
       .map(line => {
+        // set current line ident start to base reference indentation
+        let lineIdentStart = indentStart;
         // find position of 1st non-whitespace character
-        // to determine the markdown indentation start
-        if (line.length > 0 && isNaN(indentStart)) {
-          indentStart = line.search(/\S|$/);
+        // to determine the current line indentation start
+        if (line.length > 0) {
+          lineIdentStart = isNaN(lineIdentStart)
+            ? line.search(/\S|$/)
+            : Math.min(line.search(/\S|$/), lineIdentStart);
         }
-        // remove whitespaces before indentation start
-        return indentStart
-          ? line.substring(indentStart)
+        // keep 1st non-whitespace line indentation
+        // as base reference for other lines
+        if (isNaN(indentStart)) {
+          indentStart = lineIdentStart;
+        }
+        // remove whitespaces before current line indentation
+        return !!lineIdentStart
+          ? line.substring(lineIdentStart)
           : line;
       }).join('\n');
   }