Index: src/prelude/Makefile.am
===================================================================
--- src/prelude/Makefile.am	(revision 99b75cab9ca2d0b349ffcd70d0d44168d5dd4fac)
+++ src/prelude/Makefile.am	(revision dc99f38e2db7b4d28474d2e58f743e394a268368)
@@ -28,6 +28,6 @@
 
 # create forward declarations for gcc builtins
-builtins.cf : builtins.c
-	${AM_V_GEN}@BACKEND_CC@ -E -P $^ | sed -f prototypes.sed > $@
+builtins.cf : builtins.c prototypes.sed
+	${AM_V_GEN}@BACKEND_CC@ -E -P $< | sed -f prototypes.sed > $@
 
 builtins.c : builtins.def prototypes.awk
Index: src/prelude/Makefile.in
===================================================================
--- src/prelude/Makefile.in	(revision 99b75cab9ca2d0b349ffcd70d0d44168d5dd4fac)
+++ src/prelude/Makefile.in	(revision dc99f38e2db7b4d28474d2e58f743e394a268368)
@@ -424,6 +424,6 @@
 
 # create forward declarations for gcc builtins
-builtins.cf : builtins.c
-	${AM_V_GEN}@BACKEND_CC@ -E -P $^ | sed -f prototypes.sed > $@
+builtins.cf : builtins.c prototypes.sed
+	${AM_V_GEN}@BACKEND_CC@ -E -P $< | sed -f prototypes.sed > $@
 
 builtins.c : builtins.def prototypes.awk