Use CMAKE_CURRENT_* instead of PROJECT_*.

man/CMakeLists.txt

diff --git a/man/CMakeLists.txt b/man/CMakeLists.txt
index 4d8c10b..37b84a0 100644
--- a/man/CMakeLists.txt
+++ b/man/CMakeLists.txt
@@ -114,7 +114,7 @@
   #configure_file(${SOURCE_FILE} ${MAN_PAGE} COPYONLY)
   add_custom_command(OUTPUT ${MAN_PAGE}
     DEPENDS ${SOURCE_FILE}
-    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${PROJECT_SOURCE_DIR}/man/${SOURCE_FILE} ${PROJECT_BINARY_DIR}/man/${MAN_PAGE}
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_SOURCE_DIR}/${SOURCE_FILE} ${CMAKE_CURRENT_BINARY_DIR}/${MAN_PAGE}
     COMMENT "Preparing ${MAN_PAGE}"
     )
 
@@ -123,20 +123,20 @@
   string(REGEX REPLACE "[1-9]$" "mdoc" MDOC_FILE ${MAN_PAGE})
 
   # html re-generation
-  add_custom_command(OUTPUT ${PROJECT_BINARY_DIR}/man/${HTML_FILE}
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${HTML_FILE}
     DEPENDS ${MDOC_FILE}
-    COMMAND ${CMAKE_COMMAND} -DIN=${PROJECT_SOURCE_DIR}/man/${MDOC_FILE} -DOUT=${PROJECT_BINARY_DIR}/man/${HTML_FILE} -P ${PROJECT_SOURCE_DIR}/man/update-html.cmake
-    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${PROJECT_BINARY_DIR}/man/${HTML_FILE} ${PROJECT_SOURCE_DIR}/man/${HTML_FILE}
+    COMMAND ${CMAKE_COMMAND} -DIN=${CMAKE_CURRENT_SOURCE_DIR}/${MDOC_FILE} -DOUT=${CMAKE_CURRENT_BINARY_DIR}/${HTML_FILE} -P ${CMAKE_CURRENT_SOURCE_DIR}/update-html.cmake
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_BINARY_DIR}/${HTML_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/${HTML_FILE}
     )
-  list(APPEND UPDATEHTML ${PROJECT_BINARY_DIR}/man/${HTML_FILE})
+  list(APPEND UPDATEHTML ${CMAKE_CURRENT_BINARY_DIR}/${HTML_FILE})
 
   # man re-generation
-  add_custom_command(OUTPUT ${PROJECT_BINARY_DIR}/man/${MAN_FILE}
+  add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/${MAN_FILE}
     DEPENDS ${MDOC_FILE}
-    COMMAND ${CMAKE_COMMAND} -DIN=${PROJECT_SOURCE_DIR}/man/${MDOC_FILE} -DOUT=${PROJECT_BINARY_DIR}/man/${MAN_FILE} -P ${PROJECT_SOURCE_DIR}/man/update-man.cmake
-    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${PROJECT_BINARY_DIR}/man/${MAN_FILE} ${PROJECT_SOURCE_DIR}/man/${MAN_FILE}
+     COMMAND ${CMAKE_COMMAND} -DIN=${CMAKE_CURRENT_SOURCE_DIR}/${MDOC_FILE} -DOUT=${CMAKE_CURRENT_BINARY_DIR}/${MAN_FILE} -P ${CMAKE_CURRENT_SOURCE_DIR}/update-man.cmake
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different ${CMAKE_CURRENT_BINARY_DIR}/${MAN_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/${MAN_FILE}
     )
-  list(APPEND UPDATEMAN ${PROJECT_BINARY_DIR}/man/${MAN_FILE})
+  list(APPEND UPDATEMAN ${CMAKE_CURRENT_BINARY_DIR}/${MAN_FILE})
 endforeach()
 add_custom_target(man ALL DEPENDS ${MAN_PAGES})
 add_custom_target(update-man DEPENDS ${UPDATEMAN})