diff --git a/doc/CMakeLists.txt b/doc/CMakeLists.txt
index 2af32d53..0ad2d602 100644
--- a/doc/CMakeLists.txt
+++ b/doc/CMakeLists.txt
@@ -4,11 +4,13 @@ if (NOT DOXYGEN)
   return ()
 endif ()
 
+find_package(PythonInterp
+  QUIET REQUIRED)
 find_program(SPHINX_EXECUTABLE
   NAMES sphinx-build sphinx-build-3)
 add_custom_target(doc
   COMMAND ${CMAKE_COMMAND} -E env SPHINX_EXECUTABLE=${SPHINX_EXECUTABLE}
-    ${CMAKE_CURRENT_SOURCE_DIR}/build.py ${FMT_VERSION}
+    ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/build.py ${FMT_VERSION}
   SOURCES api.rst syntax.rst usage.rst build.py conf.py _templates/layout.html)
 
 install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/html/
-- 
2.25.1