1diff --git a/admin/Makefile.def b/admin/Makefile.def
2index 0395d9d4f0..932d18f102 100644
3--- a/admin/Makefile.def
4+++ b/admin/Makefile.def
5@@ -228,7 +228,11 @@ GLOBAL_DIRTY = $(builddir) *~ TAGS ChangeLog* Makefile.bak
6 # Fortran preprocessing
7
8 # Preprocessor command
9-CPP = cpp
10+ifdef GAG_CPP
11+ CPP = $(GAG_CPP)
12+else
13+ CPP = cpp
14+endif
15
16 # Preprocessor generic flags
17 GLOBAL_CPPFLAGS += -P -traditional -C