diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -169,11 +169,22 @@
 
 set(OBJ_DIR "${CMAKE_CURRENT_BINARY_DIR}/obj")
 file(MAKE_DIRECTORY "${OBJ_DIR}")
-add_custom_target(build_header
+set(BUILD_HEADER "${OBJ_DIR}/build.h")
+set(BUILD_HEADER_TMP "${BUILD_HEADER}.tmp")
+add_custom_command(
+	DEPENDS
+		"${CMAKE_SOURCE_DIR}/.git/logs/HEAD"
+		"${CMAKE_SOURCE_DIR}/share/genbuild.sh"
+	OUTPUT
+		"${BUILD_HEADER}"
 	COMMAND
 		"${CMAKE_SOURCE_DIR}/share/genbuild.sh"
-		"${OBJ_DIR}/build.h"
+		"${BUILD_HEADER_TMP}"
 		"${CMAKE_SOURCE_DIR}"
+	COMMAND
+		${CMAKE_COMMAND} -E copy_if_different "${BUILD_HEADER_TMP}" "${BUILD_HEADER}"
+	COMMAND
+		${CMAKE_COMMAND} -E remove "${BUILD_HEADER_TMP}"
 )
 
 # Because the Bitcoin ABc source code is disorganised, we
@@ -205,9 +216,11 @@
 	utilstrencodings.cpp
 	utiltime.cpp
 	util/bytevectorhash.cpp
+
+	# obj/build.h
+	"${BUILD_HEADER}"
 )
 
-add_dependencies(util build_header)
 target_compile_definitions(util PUBLIC HAVE_CONFIG_H HAVE_BUILD_INFO)
 target_include_directories(util
 	PUBLIC