diff --git a/makefile b/makefile
index 28e2945d..36610f5b 100644
--- a/makefile
+++ b/makefile
@@ -211,8 +211,8 @@ ifeq ($(WIN32),)  #*nix Environments (&& cygwin)
       NEED_COMMIT_ID = need-commit-id
     endif
     ifeq (need-commit-id,$(NEED_COMMIT_ID))
-      $isodate=$(shell git log -1 --pretty="%ai"|sed -e 's/ /T/'|sed -e 's/ //')
-      $(shell git log -1 --pretty="SIM_GIT_COMMIT_ID %H%nSIM_GIT_COMMIT_TIME $isodate" >.git-commit-id)
+      isodate=$(shell git log -1 --pretty="%ai"|sed -e 's/ /T/'|sed -e 's/ //')
+      $(shell git log -1 --pretty="SIM_GIT_COMMIT_ID %H%nSIM_GIT_COMMIT_TIME $(isodate)" >.git-commit-id)
     endif
   endif
   LTO_EXCLUDE_VERSIONS =