diff --git a/CMakeLists.txt b/CMakeLists.txt
index 122cc49..2da6ab8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -221,4 +221,5 @@ endif()
 target_link_libraries(aaruformat slog)
 
 add_subdirectory(tests)
-add_subdirectory(tool)
\ No newline at end of file
+add_subdirectory(tool)
+add_subdirectory(docs/spec)
diff --git a/docs/spec/CMakeLists.txt b/docs/spec/CMakeLists.txt
new file mode 100644
index 0000000..77217b8
--- /dev/null
+++ b/docs/spec/CMakeLists.txt
@@ -0,0 +1,40 @@
+# This file is part of the Aaru Data Preservation Suite.
+# Copyright (c) 2019-2025 Natalia Portillo.
+#
+# This library is free software; you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation; either version 2.1 of the
+# License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, see <http://www.gnu.org/licenses/>.
+
+# Find asciidoctor-pdf executable
+find_program(ASCIIDOCTOR_PDF asciidoctor-pdf)
+
+if(ASCIIDOCTOR_PDF)
+    message(STATUS "Found asciidoctor-pdf: ${ASCIIDOCTOR_PDF}")
+
+    # Add custom target to build the specification PDF
+    add_custom_target(spec
+        COMMAND ${ASCIIDOCTOR_PDF}
+            -a pdf-theme=theme.yml
+            -a "pdf-fontsdir=fonts;GEM_FONTS_DIR"
+            -a source-highlighter=rouge
+            spec.adoc
+        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+        COMMENT "Building AaruFormat specification PDF with asciidoctor-pdf"
+        VERBATIM
+    )
+
+    message(STATUS "Added 'spec' target to build the specification PDF")
+else()
+    message(STATUS "asciidoctor-pdf not found - 'spec' target will not be available")
+    message(STATUS "Install it with: gem install asciidoctor-pdf")
+endif()
+