diff --git a/src/lib/commands/edit.c b/src/lib/commands/edit.c
index 6b370b3f..2c0293d1 100644
--- a/src/lib/commands/edit.c
+++ b/src/lib/commands/edit.c
@@ -975,7 +975,7 @@ dounit(char op, int arg, char *p, struct lndstr *land)
 }
 
 
-int
+static int
 doplane(char op, int arg, char *p, struct plnstr *plane)
 {
     coord newx, newy;
diff --git a/src/lib/common/hours.c b/src/lib/common/hours.c
index 52d29d38..96500bce 100644
--- a/src/lib/common/hours.c
+++ b/src/lib/common/hours.c
@@ -142,7 +142,7 @@ weekday(char *str, int *wday)
  * Else return NULL.
  * Time format is HOUR:MINUTE.  Initial whitespace is ignored.
  */
-char *
+static char *
 daytime(char *str, int *min)
 {
     /*
@@ -177,7 +177,7 @@ daytime(char *str, int *min)
  * Else return NULL.
  * Format is HOUR:MINUTE-HOUR:MINUTE.  Initial whitespace is ignored.
  */
-char *
+static char *
 daytime_range(char *str, int *from_min, int *to_min)
 {
     char *end;
diff --git a/src/lib/subs/aircombat.c b/src/lib/subs/aircombat.c
index d5dbbc85..9a91173a 100644
--- a/src/lib/subs/aircombat.c
+++ b/src/lib/subs/aircombat.c
@@ -399,7 +399,7 @@ ac_intercept(struct emp_qelem *bomb_list, struct emp_qelem *esc_list,
     pln_put(&int_list);
 }
 
-void
+static void
 ac_combat_headers(natid plane_owner, natid def_own)
 {
     PR(plane_owner,
@@ -413,7 +413,7 @@ ac_combat_headers(natid plane_owner, natid def_own)
 /*
  * air-to-air combat.
  */
-void
+static void
 ac_airtoair(struct emp_qelem *att_list, struct emp_qelem *int_list)
 {
     struct plist *attacker;