diff --git a/CHANGELOG.md b/CHANGELOG.md
index 07293805..8182b0a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 # Changelog
 ## [Unreleased]
 
+### Added
+
+- **PlantUML support**: `.puml`, `.plantuml`, and `.pu` files are now indexed as `plantuml` code blocks
+
 ## [0.34.0] - 2026-03-13
 
 ### Added
diff --git a/docs/server.md b/docs/server.md
index 3f6ba3ef..40bd46b4 100644
--- a/docs/server.md
+++ b/docs/server.md
@@ -109,6 +109,7 @@ The file monitor processes documents using [Docling](https://github.com/DS4SD/do
 - Python (`.py`)
 - JavaScript (`.js`)
 - TypeScript (`.ts`)
+- PlantUML (`.puml`, `.plantuml`, `.pu`)
 - And other text-based code files
 
 **Plain text:**
diff --git a/haiku_rag_slim/haiku/rag/converters/text_utils.py b/haiku_rag_slim/haiku/rag/converters/text_utils.py
index eb521b50..270ddf1f 100644
--- a/haiku_rag_slim/haiku/rag/converters/text_utils.py
+++ b/haiku_rag_slim/haiku/rag/converters/text_utils.py
@@ -54,8 +54,11 @@ class TextFileHandler:
         ".nix",
         ".php",
         ".pl",
+        ".plantuml",
         ".pm",
         ".proto",
+        ".pu",
+        ".puml",
         ".ps1",
         ".py",
         ".r",
@@ -118,8 +121,11 @@ class TextFileHandler:
         ".nix": "nix",
         ".php": "php",
         ".pl": "perl",
+        ".plantuml": "plantuml",
         ".pm": "perl",
         ".proto": "protobuf",
+        ".pu": "plantuml",
+        ".puml": "plantuml",
         ".ps1": "powershell",
         ".py": "python",
         ".r": "r",
diff --git a/tests/test_converters.py b/tests/test_converters.py
index 7775cf09..c5a8435c 100644
--- a/tests/test_converters.py
+++ b/tests/test_converters.py
@@ -89,12 +89,24 @@ class TestTextFileHandler:
         assert ".js" in TextFileHandler.text_extensions
         assert ".txt" in TextFileHandler.text_extensions
 
+    def test_plantuml_extensions_supported(self):
+        """Test that PlantUML extensions are in text_extensions."""
+        assert ".puml" in TextFileHandler.text_extensions
+        assert ".plantuml" in TextFileHandler.text_extensions
+        assert ".pu" in TextFileHandler.text_extensions
+
     def test_code_markdown_identifiers(self):
         """Test code language identifiers mapping."""
         assert TextFileHandler.code_markdown_identifier[".py"] == "python"
         assert TextFileHandler.code_markdown_identifier[".js"] == "javascript"
         assert TextFileHandler.code_markdown_identifier[".ts"] == "typescript"
 
+    def test_plantuml_markdown_identifiers(self):
+        """Test PlantUML language identifiers mapping."""
+        assert TextFileHandler.code_markdown_identifier[".puml"] == "plantuml"
+        assert TextFileHandler.code_markdown_identifier[".plantuml"] == "plantuml"
+        assert TextFileHandler.code_markdown_identifier[".pu"] == "plantuml"
+
     def test_prepare_text_content_with_code(self):
         """Test that code files are wrapped in markdown code blocks."""
         code = "def hello():\n    pass"
@@ -103,6 +115,14 @@ class TestTextFileHandler:
         assert result.endswith("\n```")
         assert "def hello():" in result
 
+    def test_prepare_text_content_with_plantuml(self):
+        """Test that PlantUML files are wrapped in plantuml code blocks."""
+        puml = "@startuml\nAlice -> Bob: Hello\n@enduml"
+        result = TextFileHandler.prepare_text_content(puml, ".puml")
+        assert result.startswith("```plantuml\n")
+        assert result.endswith("\n```")
+        assert "@startuml" in result
+
     def test_prepare_text_content_without_code(self):
         """Test that plain text files are not wrapped."""
         text = "Hello world"