diff --git a/CMakeFiles/Docs.cmake b/CMakeFiles/Docs.cmake
index 34c3ee940..aac93564f 100644
--- a/CMakeFiles/Docs.cmake
+++ b/CMakeFiles/Docs.cmake
@@ -66,9 +66,10 @@ ADD_CUSTOM_COMMAND(OUTPUT doc_src/index.hdr
                    DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/toc.txt)
 
 ADD_CUSTOM_TARGET(doc
-                  COMMAND "(cat Doxyfile.user; echo INPUT_FILTER=./lexicon_filter; echo PROJECT_NUMBER=${FISH_BUILD_VERSION} |\
-                           /usr/bin/env sed 's/-.*//') | doxygen - && touch user_doc)"
-                  DEPENDS Doxyfile.user ${DOC_SRC_FILES} doc.h $(HDR_FILES) lexicon_filter)
+                  COMMAND env "$$(cat" "FISH-BUILD-VERSION-FILE)"
+                          ${CMAKE_CURRENT_SOURCE_DIR}/build_tools/build_user_doc.sh
+                          ${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile.user ./lexicon_filter
+                  DEPENDS "FISH-BUILD-VERSION-FILE" Doxyfile.user ${DOC_SRC_FILES} doc.h $(HDR_FILES) lexicon_filter)
 
 # doc: $(HDR_FILES_SRC) Doxyfile.user $(HTML_SRC) $(HELP_SRC) doc.h $(HDR_FILES) lexicon_filter
 #   @echo "  doxygen  $(em)user_doc$(sgr0)"
diff --git a/Makefile.in b/Makefile.in
index 7a67928b8..41aa362f6 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -317,8 +317,7 @@ prof: all
 #
 doc: $(HDR_FILES_SRC) Doxyfile.user $(HTML_SRC) $(HELP_SRC) doc.h $(HDR_FILES) lexicon_filter
 	@echo "  doxygen  $(em)user_doc$(sgr0)"
-	$v (cat Doxyfile.user; echo INPUT_FILTER=./lexicon_filter; echo PROJECT_NUMBER=$(FISH_BUILD_VERSION) | $(SED) "s/-.*//") | doxygen - && touch user_doc
-	$v rm -f $(wildcard $(addprefix ./user_doc/html/,arrow*.png bc_s.png bdwn.png closed.png doc.png folder*.png ftv2*.png nav*.png open.png splitbar.png sync_*.png tab*.* doxygen.* dynsections.js jquery.js pages.html))
+	$v env FISH_BUILD_VERSION=$(FISH_BUILD_VERSION) ./build_tools/build_user_doc.sh Doxyfile.user ./lexicon_filter
 
 #
 # PDF version of the source code documentation.
diff --git a/build_tools/build_user_doc.sh b/build_tools/build_user_doc.sh
new file mode 100755
index 000000000..d6c043889
--- /dev/null
+++ b/build_tools/build_user_doc.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Usage: Doxyfile.user lexicon_filter
+DOXYFILE=$1
+LEXICON_FILTER=$2
+
+(cat "${DOXYFILE}" ;\
+ echo INPUT_FILTER="${LEXICON_FILTER}"; \
+ echo PROJECT_NUMBER=${FISH_BUILD_VERSION} \
+ | /usr/bin/env sed "s/-.*//") \
+   | doxygen - && touch user_doc
+
+(cd ./user_doc/html/ && \
+ rm -f bc_s.png bdwn.png closed.png doc.png folder*.png ftv2*.png \
+       nav*.png open.png splitbar.png sync_*.png tab*.* doxygen.* \
+       dynsections.js jquery.js pages.html)