--- file_not_specified_in_diff	
+++ file_not_specified_in_diff	
@@ -, +, @@ 
--- common.mk
+++ common.mk
@@ -50,7 +50,7 @@ 
 	guile-snarf $(GUILE_SNARF_CFLAGS) $< > $@ \
 	|| { rm $@; false; }
 .c.doc:
-	$(CPP) -DSCM_MAGIC_SNARF_DOCS $(GUILE_SNARF_CFLAGS) $< \
+	$(CPP) -P -DSCM_MAGIC_SNARF_DOCS $(GUILE_SNARF_CFLAGS) $< \
 	  | grep -E '^\^\^ {.*\^\^ }' > $@ || { rm $@; false; }
 
 %.scm guile-gnome-gw-%.c: %-spec.scm