diff --git a/CMakeLists.txt b/CMakeLists.txt
index 062b382e..359921ec 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,7 +28,9 @@ if(GIT_FOUND)
         WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
         OUTPUT_VARIABLE GIT_COMMIT_STRING
         OUTPUT_STRIP_TRAILING_WHITESPACE)
-else()
+endif()
+
+if(NOT GIT_COMMIT_STRING)
     set(GIT_COMMIT_STRING "unknown")
 endif()