diff --git a/buchi.c b/buchi.c
index 3f15e3d..fd187ae 100644
--- a/buchi.c
+++ b/buchi.c
@@ -45,8 +45,9 @@ extern void put_uform(void);
 
 extern FILE *tl_out;	
 BState *bstack, *bstates, *bremoved;
-BScc *scc_stack;
-int bstate_count = 0, btrans_count = 0, rank;
+static BScc *scc_stack;
+int bstate_count = 0, btrans_count = 0;
+static int rank;
 
 static int _accept;
 
diff --git a/generalized.c b/generalized.c
index 4be7a04..74a881c 100644
--- a/generalized.c
+++ b/generalized.c
@@ -46,9 +46,10 @@ extern int tl_verbose, tl_stats, tl_simp_diff, tl_simp_fly, tl_fjtofj,
 extern char **sym_table;
 
 GState *gstack, *gremoved, *gstates, **init;
-GScc *scc_stack;
+static GScc *scc_stack;
 int init_size = 0, gstate_id = 1, gstate_count = 0, gtrans_count = 0;
-int *fin, *final, rank, scc_id, scc_size, *bad_scc;
+int *fin, *final, scc_id, scc_size, *bad_scc;
+static int rank;
 
 void print_generalized();