diff --git a/cmake/GetGitVersion.cmake b/cmake/GetGitVersion.cmake
index 8dd94800..88cebe3a 100644
--- a/cmake/GetGitVersion.cmake
+++ b/cmake/GetGitVersion.cmake
@@ -21,6 +21,7 @@ set(__get_git_version INCLUDED)
 function(get_git_version var)
   if(GIT_EXECUTABLE)
       execute_process(COMMAND ${GIT_EXECUTABLE} describe --match "v[0-9]*.[0-9]*.[0-9]*" --abbrev=8
+          WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
           RESULT_VARIABLE status
           OUTPUT_VARIABLE GIT_VERSION
           ERROR_QUIET)
@@ -33,9 +34,11 @@ function(get_git_version var)
 
       # Work out if the repository is dirty
       execute_process(COMMAND ${GIT_EXECUTABLE} update-index -q --refresh
+          WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
           OUTPUT_QUIET
           ERROR_QUIET)
       execute_process(COMMAND ${GIT_EXECUTABLE} diff-index --name-only HEAD --
+          WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
           OUTPUT_VARIABLE GIT_DIFF_INDEX
           ERROR_QUIET)
       string(COMPARE NOTEQUAL "${GIT_DIFF_INDEX}" "" GIT_DIRTY)