diff --git a/coreapi/help/doc/doxygen/CMakeLists.txt b/coreapi/help/doc/doxygen/CMakeLists.txt
index 95a5528ea..8d066161b 100644
--- a/coreapi/help/doc/doxygen/CMakeLists.txt
+++ b/coreapi/help/doc/doxygen/CMakeLists.txt
@@ -36,6 +36,7 @@ if (ENABLE_DOC OR ENABLE_CXX_WRAPPER OR ENABLE_CSHARP_WRAPPER OR ENABLE_JAVA_WRA
 			string(CONCAT DOXYGEN_INPUT ${DOXYGEN_INPUT} " \"${PROJECT_SOURCE_DIR}/coreapi/help/examples/C\"")
 			configure_file(${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.in ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)
 			add_custom_command(OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/html/index.html" "${CMAKE_CURRENT_BINARY_DIR}/xml/index.xml"
+				COMMAND ${CMAKE_COMMAND} -E remove -f html/* xml/*
 				COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile
 				DEPENDS ${DOC_INPUT_FILES}
 			)
@@ -51,3 +52,4 @@ if (ENABLE_DOC OR ENABLE_CXX_WRAPPER OR ENABLE_CSHARP_WRAPPER OR ENABLE_JAVA_WRA
 		endif ()
 	endif ()
 endif ()
+