diff --git a/include/ship.h b/include/ship.h
index 1b265e9c..46759d5f 100644
--- a/include/ship.h
+++ b/include/ship.h
@@ -215,7 +215,7 @@ struct mlist {
 
 enum {
     SHP_AIROPS_EFF = 50,	/* min. efficiency for air ops */
-    M_TORP_SHELLS = 3		/* number of shells used by a torpedo */
+    SHP_TORP_SHELLS = 3		/* number of shells used by a torpedo */
 };
 
 #endif /* _SHIP_H_ */
diff --git a/src/lib/commands/mfir.c b/src/lib/commands/mfir.c
index 05799837..c98e7571 100644
--- a/src/lib/commands/mfir.c
+++ b/src/lib/commands/mfir.c
@@ -811,10 +811,10 @@ quiet_bigdef(int attacker, struct emp_qelem *list, natid own, natid aown,
 	    continue;
 
 	if (mchr[(int)ship.shp_type].m_flags & M_SUB) {
-	    if (shell < M_TORP_SHELLS)
+	    if (shell < SHP_TORP_SHELLS)
 		shell += supply_commod(ship.shp_own, ship.shp_x, ship.shp_y,
-				       I_SHELL, M_TORP_SHELLS - shell);
-	    if (shell < M_TORP_SHELLS)
+				       I_SHELL, SHP_TORP_SHELLS - shell);
+	    if (shell < SHP_TORP_SHELLS)
 		continue;
 	    if (gun < 1)
 		continue;
@@ -1008,7 +1008,7 @@ use_ammo(struct emp_qelem *list)
 	    item = ship.shp_item;
 	    if (mchr[(int)ship.shp_type].m_flags & M_SUB) {
 		shell = item[I_SHELL];
-		shell -= M_TORP_SHELLS - 1;
+		shell -= SHP_TORP_SHELLS - 1;
 		if (shell < 0)
 		    shell = 0;
 		item[I_SHELL] = shell;
diff --git a/src/lib/commands/torp.c b/src/lib/commands/torp.c
index 01261df8..cb03d663 100644
--- a/src/lib/commands/torp.c
+++ b/src/lib/commands/torp.c
@@ -88,10 +88,10 @@ torp(void)
 	if ((mchr[(int)sub.shp_type].m_flags & M_TORP) == 0)
 	    continue;
 	shells = sub.shp_item[I_SHELL];
-	if (shells < M_TORP_SHELLS)
+	if (shells < SHP_TORP_SHELLS)
 	    shells += supply_commod(sub.shp_own, sub.shp_x, sub.shp_y,
-				    I_SHELL, M_TORP_SHELLS - shells);
-	if (sub.shp_item[I_GUN] == 0 || shells < M_TORP_SHELLS)
+				    I_SHELL, SHP_TORP_SHELLS - shells);
+	if (sub.shp_item[I_GUN] == 0 || shells < SHP_TORP_SHELLS)
 	    continue;
 	if (sub.shp_item[I_MILIT] < 1)
 	    continue;
@@ -115,10 +115,10 @@ torp(void)
 	    continue;
 	}
 	shells = sub.shp_item[I_SHELL];
-	if (shells < M_TORP_SHELLS)
+	if (shells < SHP_TORP_SHELLS)
 	    shells += supply_commod(sub.shp_own, sub.shp_x, sub.shp_y,
-				    I_SHELL, M_TORP_SHELLS - shells);
-	if (sub.shp_item[I_GUN] == 0 || shells < M_TORP_SHELLS) {
+				    I_SHELL, SHP_TORP_SHELLS - shells);
+	if (sub.shp_item[I_GUN] == 0 || shells < SHP_TORP_SHELLS) {
 	    pr("Ship #%d has insufficient armament\n", sub.shp_uid);
 	    continue;
 	}
@@ -167,7 +167,7 @@ torp(void)
 	    techfact(sub.shp_tech, ((double)sub.shp_frnge));
 	erange = (double)roundrange(erange);
 	pr("Effective torpedo range is %.1f\n", erange);
-	shells -= M_TORP_SHELLS;
+	shells -= SHP_TORP_SHELLS;
 	sub.shp_item[I_SHELL] = shells;
 	putship(sub.shp_uid, &sub);
 	mcp = &mchr[(int)sub.shp_type];
@@ -407,11 +407,11 @@ fire_torp(struct shpstr *sp, struct shpstr *targ, int range, int ntargets)
 
     shells = sp->shp_item[I_SHELL];
 
-    if (shells < M_TORP_SHELLS)
+    if (shells < SHP_TORP_SHELLS)
 	shells += supply_commod(sp->shp_own, sp->shp_x, sp->shp_y, I_SHELL,
-				M_TORP_SHELLS - shells);
+				SHP_TORP_SHELLS - shells);
 
-    if (sp->shp_item[I_GUN] == 0 || shells < M_TORP_SHELLS)
+    if (sp->shp_item[I_GUN] == 0 || shells < SHP_TORP_SHELLS)
 	return 0;
 
     if (sp->shp_item[I_MILIT] < 1)
@@ -424,7 +424,7 @@ fire_torp(struct shpstr *sp, struct shpstr *targ, int range, int ntargets)
 	return 0;
 
     /* All set.. fire! */
-    shells -= M_TORP_SHELLS;
+    shells -= SHP_TORP_SHELLS;
     sp->shp_item[I_SHELL] = shells;
     putship(sp->shp_uid, sp);
 
diff --git a/src/lib/subs/mission.c b/src/lib/subs/mission.c
index 114ef2b7..8b0f55bc 100644
--- a/src/lib/subs/mission.c
+++ b/src/lib/subs/mission.c
@@ -562,11 +562,11 @@ perform_mission(coord x, coord y, natid victim, struct emp_qelem *list,
 		if (gun < 1)
 		    continue;
 		shell = sp->shp_item[I_SHELL];
-		if (shell < M_TORP_SHELLS)
+		if (shell < SHP_TORP_SHELLS)
 		    shell += supply_commod(sp->shp_own,
 					   sp->shp_x, sp->shp_y, I_SHELL,
-					   M_TORP_SHELLS - shell);
-		if (shell < M_TORP_SHELLS)
+					   SHP_TORP_SHELLS - shell);
+		if (shell < SHP_TORP_SHELLS)
 		    continue;
 
 		range = sp->shp_effic * techfact(sp->shp_tech,
@@ -579,7 +579,7 @@ perform_mission(coord x, coord y, natid victim, struct emp_qelem *list,
 
 		if (!line_of_sight((s_char **)0, x, y, gp->x, gp->y))
 		    continue;
-		sp->shp_item[I_SHELL] = shell - M_TORP_SHELLS;
+		sp->shp_item[I_SHELL] = shell - SHP_TORP_SHELLS;
 		mobcost = sp->shp_effic * 0.01 * sp->shp_speed;
 		mobcost = (480.0 / (mobcost +
 				    techfact(sp->shp_tech, mobcost)));