diff --git a/mach/6500/libbc/Makefile b/mach/6500/libbc/Makefile
index 2be55a0ab..6bc856bb5 100644
--- a/mach/6500/libbc/Makefile
+++ b/mach/6500/libbc/Makefile
@@ -1,5 +1,6 @@
+SUF=s
 MAKEFILE=../../proto/libg/Makefile
-MACHDEF="MACH=6500" "SUF=s"
+MACHDEF="MACH=6500" "SUF=$(SUF)"
 BCDEF="PREF=bc" "SUB=" "SRC=lang/basic/lib"
 
 install:
diff --git a/mach/6500/libcc/Makefile b/mach/6500/libcc/Makefile
index 7b71f6568..df0b2b353 100644
--- a/mach/6500/libcc/Makefile
+++ b/mach/6500/libcc/Makefile
@@ -1,5 +1,6 @@
+SUF=s
 MAKEFILE=../../proto/libg/Makefile
-MACHDEF="MACH=6500" "SUF=s"
+MACHDEF="MACH=6500" "SUF=$(SUF)"
 STDIO="PREF=cc" "SUB=.1s" "SRC=lang/cem/libcc/stdio"
 GEN="PREF=cc" "SUB=.2g" "SRC=lang/cem/libcc/gen"
 MON="PREF=mon" "SRC=lang/cem/libcc/mon"
diff --git a/mach/6500/libpc/Makefile b/mach/6500/libpc/Makefile
index 13271c218..af1866ee1 100644
--- a/mach/6500/libpc/Makefile
+++ b/mach/6500/libpc/Makefile
@@ -1,5 +1,6 @@
+SUF=s
 MAKEFILE=../../proto/libg/Makefile
-MACHDEF="MACH=6500" "SUF=s"
+MACHDEF="MACH=6500" "SUF=$(SUF)"
 PCDEF="PREF=pc" "SUB=" "SRC=lang/pc/libpc"
 
 install: