diff --git a/admin/Makefile.def b/admin/Makefile.def
index 27a1c02..43ef322 100644
--- a/admin/Makefile.def
+++ b/admin/Makefile.def
@@ -228,7 +228,7 @@ GLOBAL_DIRTY = $(builddir) *~ TAGS ChangeLog* Makefile.bak
 # Fortran preprocessing
 
 # Preprocessor command
-CPP = cpp
+CPP = $(GAG_CPP)
 
 # Preprocessor generic flags
 GLOBAL_CPPFLAGS += -P -traditional -C