diff --git a/GitVersionGen/GetGitRevisionDescription.cmake b/GitVersionGen/GetGitRevisionDescription.cmake
index 00f8727..2b4a479 100644
--- a/GitVersionGen/GetGitRevisionDescription.cmake
+++ b/GitVersionGen/GetGitRevisionDescription.cmake
@@ -58,7 +58,7 @@ function(get_git_head_revision _refspecvar _hashvar)
 		file(READ ${GIT_DIR} submodule)
 		string(REGEX REPLACE "gitdir: (.*)\n$" "\\1" GIT_DIR_RELATIVE ${submodule})
 		get_filename_component(SUBMODULE_DIR ${GIT_DIR} PATH)
-		get_filename_component(GIT_DIR ${SUBMODULE_DIR}/${GIT_DIR_RELATIVE} ABSOLUTE)
+		get_filename_component(GIT_DIR ${GIT_DIR_RELATIVE} ABSOLUTE BASE_DIR ${SUBMODULE_DIR})
 	endif()
 	set(GIT_DATA "${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/git-data")
 	if(NOT EXISTS "${GIT_DATA}")