diff --git a/strictdoc/export/html/generators/source_file_view_generator.py b/strictdoc/export/html/generators/source_file_view_generator.py
index de36ccde1..ac485ce19 100644
--- a/strictdoc/export/html/generators/source_file_view_generator.py
+++ b/strictdoc/export/html/generators/source_file_view_generator.py
@@ -1,5 +1,5 @@
 # mypy: disable-error-code="no-untyped-call,no-untyped-def,operator"
-from typing import List, Tuple
+from typing import List, Tuple, Union
 
 from markupsafe import Markup, escape
 from pygments import highlight
@@ -28,10 +28,13 @@
 from strictdoc.core.traceability_index import TraceabilityIndex
 from strictdoc.export.html.generators.view_objects.source_file_view_object import (
     SourceFileViewObject,
+    SourceLineEntry,
+    SourceMarkerTuple,
 )
 from strictdoc.export.html.html_templates import HTMLTemplates
 from strictdoc.export.html.renderers.link_renderer import LinkRenderer
 from strictdoc.export.html.renderers.markup_renderer import MarkupRenderer
+from strictdoc.helpers.cast import assert_cast
 
 
 class SourceFileViewHTMLGenerator:
@@ -46,7 +49,7 @@ def export(
         with open(source_file.full_path, encoding="utf-8") as opened_file:
             source_file_lines = opened_file.readlines()
 
-        pygmented_source_file_lines: List[Markup] = []
+        pygmented_source_file_lines: List[SourceLineEntry] = []
         pygments_styles: Markup = Markup("")
 
         if len(source_file_lines) > 0:
@@ -89,7 +92,10 @@ def get_pygmented_source_lines(
         source_file: SourceFile,
         source_file_lines: List[str],
         coverage_info: SourceFileTraceabilityInfo,
-    ) -> Tuple[List[Markup], Markup]:
+    ) -> Tuple[
+        List[SourceLineEntry],
+        Markup,
+    ]:
         assert isinstance(source_file, SourceFile)
         assert isinstance(source_file_lines, list)
         assert isinstance(coverage_info, SourceFileTraceabilityInfo)
@@ -154,7 +160,9 @@ def get_pygmented_source_lines(
         pygmented_source_file_content = pygmented_source_file_content[
             slice_start:slice_end
         ]
-        pygmented_source_file_lines = pygmented_source_file_content.split("\n")
+        pygmented_source_file_lines: List[Union[str, SourceMarkerTuple]] = list(
+            pygmented_source_file_content.split("\n")
+        )
         if hack_first_line:
             pygmented_source_file_lines[0] = "<span></span>"
 
@@ -177,12 +185,14 @@ def get_pygmented_source_lines(
 
         for pragma in coverage_info.pragmas:
             pragma_line = pragma.ng_source_line_begin
+            assert isinstance(pragma_line, int)
+            pygmented_source_file_line = assert_cast(
+                pygmented_source_file_lines[pragma_line - 1], str
+            )
             if isinstance(pragma, ForwardRangeMarker):
+                before_line = pygmented_source_file_line.rstrip("\n") + " "
                 pygmented_source_file_lines[pragma_line - 1] = (
-                    pygmented_source_file_lines[pragma_line - 1].rstrip("\n")
-                    + " ",
-                    "\n",
-                    pragma,
+                    SourceMarkerTuple(Markup(before_line), Markup("\n"), pragma)
                 )
                 continue
 
@@ -202,7 +212,7 @@ def get_pygmented_source_lines(
             assert closing_bracket_index is not None
             after_line = source_line[closing_bracket_index:].rstrip()
 
-            pygmented_source_file_lines[pragma_line - 1] = (
+            pygmented_source_file_lines[pragma_line - 1] = SourceMarkerTuple(
                 escape(before_line),
                 escape(after_line),
                 pragma,
@@ -212,6 +222,13 @@ def get_pygmented_source_lines(
             + html_formatter.get_style_defs(".highlight")
         )
 
-        return list(map(Markup, pygmented_source_file_lines)), Markup(
-            pygments_styles
-        )
+        return [
+            SourceFileViewHTMLGenerator.mark_safe(line)
+            for line in pygmented_source_file_lines
+        ], Markup(pygments_styles)
+
+    @staticmethod
+    def mark_safe(
+        line: Union[str, SourceMarkerTuple],
+    ) -> Union[Markup, SourceMarkerTuple]:
+        return line if isinstance(line, SourceMarkerTuple) else Markup(line)
diff --git a/strictdoc/export/html/generators/view_objects/source_file_view_object.py b/strictdoc/export/html/generators/view_objects/source_file_view_object.py
index 9ff0dbbb8..d5dea0060 100644
--- a/strictdoc/export/html/generators/view_objects/source_file_view_object.py
+++ b/strictdoc/export/html/generators/view_objects/source_file_view_object.py
@@ -1,11 +1,16 @@
 # mypy: disable-error-code="no-any-return,no-untyped-call,no-untyped-def,union-attr"
 from dataclasses import dataclass
 from datetime import datetime
-from typing import List
+from typing import List, NamedTuple, Union
 
 from markupsafe import Markup
 
 from strictdoc import __version__
+from strictdoc.backend.sdoc_source_code.models.range_marker import (
+    ForwardRangeMarker,
+    LineMarker,
+    RangeMarker,
+)
 from strictdoc.core.document_tree_iterator import DocumentTreeIterator
 from strictdoc.core.finders.source_files_finder import SourceFile
 from strictdoc.core.project_config import ProjectConfig
@@ -15,6 +20,18 @@
 from strictdoc.export.html.renderers.markup_renderer import MarkupRenderer
 
 
+class SourceMarkerTuple(NamedTuple):
+    before_line: Markup
+    after_line: Markup
+    pragma: Union[ForwardRangeMarker, LineMarker, RangeMarker]
+
+
+SourceLineEntry = Union[
+    Markup,
+    SourceMarkerTuple,
+]
+
+
 @dataclass
 class SourceFileViewObject:
     def __init__(
@@ -26,7 +43,7 @@ def __init__(
         markup_renderer: MarkupRenderer,
         source_file: SourceFile,
         pygments_styles: Markup,
-        pygmented_source_file_lines: List[Markup],
+        pygmented_source_file_lines: List[SourceLineEntry],
     ):
         self.traceability_index: TraceabilityIndex = traceability_index
         self.project_config: ProjectConfig = project_config
@@ -34,7 +51,7 @@ def __init__(
         self.markup_renderer: MarkupRenderer = markup_renderer
         self.source_file: SourceFile = source_file
         self.pygments_styles: Markup = pygments_styles
-        self.pygmented_source_file_lines: List[Markup] = (
+        self.pygmented_source_file_lines: List[SourceLineEntry] = (
             pygmented_source_file_lines
         )
 
diff --git a/strictdoc/export/html/templates/screens/source_file_view/main.jinja b/strictdoc/export/html/templates/screens/source_file_view/main.jinja
index 1e627a751..52a5696ae 100644
--- a/strictdoc/export/html/templates/screens/source_file_view/main.jinja
+++ b/strictdoc/export/html/templates/screens/source_file_view/main.jinja
@@ -6,7 +6,7 @@
     {%- for line in view_object.pygmented_source_file_lines -%}
       <div id="line-{{ loop.index }}" class="source__line-number"><pre>{{ loop.index }}</pre></div>
       <div data-line={{ loop.index }} class="source__line-content">
-        {%- if line.__class__.__name__ == "tuple" -%}
+        {%- if line.__class__.__name__ == "SourceMarkerTuple" -%}
           {%- set replacement_before, replacement_after, pragma = line -%}
           {# Note: Cannot format HTML/Jinja blocks within 'pre' tags! #}
           <pre class="sdoc-comment">{{ replacement_before }}{%- for req in pragma.reqs_objs -%}