diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2d5079..55b641e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1 +1,4 @@
+- Added `Insert chapter marker` button in text editor to insert chapter markers at the current cursor position.
+- Fixed `f-string: unmatched '['` error in Voice preview, mentioned in #14
+- Fixed the content before first chapter not being included in the output (added handling for initial content).
 - Fixed m4b chapter generation opens CMD window in Windows.
\ No newline at end of file
diff --git a/abogen/conversion.py b/abogen/conversion.py
index 0be2f26..863a05a 100644
--- a/abogen/conversion.py
+++ b/abogen/conversion.py
@@ -228,6 +228,12 @@ class ConversionThread(QThread):
             chapter_splits = list(re.finditer(chapter_pattern, text))
             chapters = []
             if chapter_splits:
+                # prepend Introduction for content before first marker
+                first_start = chapter_splits[0].start()
+                if first_start > 0:
+                    intro_text = text[:first_start].strip()
+                    if intro_text:
+                        chapters.append(("Introduction", intro_text))
                 for idx, match in enumerate(chapter_splits):
                     start = match.end()
                     end = (
@@ -628,9 +634,9 @@ class ConversionThread(QThread):
                 f.write(f"[CHAPTER]\n")
                 f.write(f"TIMEBASE=1/10\n")
                 # use 10th of second for start/end time
-                f.write(f"START={int(chapter["start"]*10)}\n")
-                f.write(f"END={int(chapter["end"]*10)}\n")
-                f.write(f"title={chapter["chapter"]}\n\n")
+                f.write(f"START={int(chapter['start']*10)}\n")
+                f.write(f"END={int(chapter['end']*10)}\n")
+                f.write(f"title={chapter['chapter']}\n\n")
         # call ffmpeg to merge the chapters into the output file
         # ffmpeg installed on first call to add_paths()
         static_ffmpeg.add_paths()
diff --git a/abogen/gui.py b/abogen/gui.py
index 6bbc607..544def1 100644
--- a/abogen/gui.py
+++ b/abogen/gui.py
@@ -358,6 +358,11 @@ class TextboxDialog(QDialog):
         self.save_as_button.clicked.connect(self.save_as_text)
         self.save_as_button.setToolTip("Save the current text to a file")
 
+        self.insert_chapter_btn = QPushButton("Insert Chapter Marker", self)
+        self.insert_chapter_btn.setToolTip("Insert a chapter marker at the cursor")
+        self.insert_chapter_btn.clicked.connect(self.insert_chapter_marker)
+        button_layout.addWidget(self.insert_chapter_btn)
+
         self.cancel_button = QPushButton("Cancel", self)
         self.cancel_button.clicked.connect(self.reject)
 
@@ -444,6 +449,13 @@ class TextboxDialog(QDialog):
         except Exception as e:
             QMessageBox.critical(self, "Save Error", f"Could not save file:\n{e}")
 
+    def insert_chapter_marker(self):
+        # Insert a fixed chapter marker without prompting
+        cursor = self.text_edit.textCursor()
+        cursor.insertText("<<CHAPTER_MARKER:Chapter Title>>")
+        self.text_edit.setTextCursor(cursor)
+        self.update_char_count()
+
 
 class abogen(QWidget):
     def __init__(self):
@@ -2126,3 +2138,4 @@ class abogen(QWidget):
                 "Setting Saved",
                 f"Maximum words per subtitle set to {value}.",
             )
+