diff --git a/include/sect.h b/include/sect.h
index 3db52198..6cfcef69 100644
--- a/include/sect.h
+++ b/include/sect.h
@@ -188,6 +188,8 @@ extern struct dchrstr bigcity_dchr;
 #define CHE_MAX 255
 /* maximum number of mines, must fit into struct sctstr member sct_mines */
 #define MINES_MAX 65535
+/* maximum fallout, must fit into struct sctstr member sct_fallout */
+#define FALLOUT_MAX 9999
 
 /* Each cost is per point of efficency */
 struct sctintrins {
diff --git a/src/lib/commands/edit.c b/src/lib/commands/edit.c
index 274c0075..c5064ac8 100644
--- a/src/lib/commands/edit.c
+++ b/src/lib/commands/edit.c
@@ -616,7 +616,7 @@ doland(s_char op, int arg, s_char *p, struct sctstr *sect)
 	break;
     case 'F':
 	old = sect->sct_fallout;
-	new = errcheck(arg, 0, 9999);
+	new = errcheck(arg, 0, FALLOUT_MAX);
 	pr("Fallout for sector %s changed from %d to %d\n",
 	   xyas(sect->sct_x, sect->sct_y, player->cnum), old, new);
 	sect->sct_fallout = new;
diff --git a/src/lib/subs/detonate.c b/src/lib/subs/detonate.c
index 3265410d..b1b3dbac 100644
--- a/src/lib/subs/detonate.c
+++ b/src/lib/subs/detonate.c
@@ -112,7 +112,7 @@ detonate(struct plnstr *pp, int x, int y)
 		fallout += damage * 30;
 	    else
 		fallout += damage * 3;
-	    sect.sct_fallout = fallout;
+	    sect.sct_fallout = min(fallout, FALLOUT_MAX);
 	}
 	if (damage > 100) {
 	    makelost(EF_SECTOR, sect.sct_own, 0, sect.sct_x, sect.sct_y);
diff --git a/src/lib/update/sect.c b/src/lib/update/sect.c
index 4ae30aed..01e63c06 100644
--- a/src/lib/update/sect.c
+++ b/src/lib/update/sect.c
@@ -307,7 +307,7 @@ spread_fallout(struct sctstr *sp, int etus)
 #endif
 	if (inc < 0)
 	    inc = 0;
-	ap->sct_fallout += inc;
+	ap->sct_fallout = min(ap->sct_fallout + inc, FALLOUT_MAX);
     }
 }
 
@@ -327,8 +327,7 @@ decay_fallout(struct sctstr *sp, int etus)
 	   sp->sct_y, decay, sp->sct_fallout);
 #endif
 
-    sp->sct_fallout =
-	(decay < sp->sct_fallout) ? (sp->sct_fallout - decay) : 0;
+    sp->sct_fallout = decay < sp->sct_fallout ? sp->sct_fallout - decay : 0;
 }
 
 #define SHOULD_PRODUCE(sp,t)	(((sp->sct_type == t) || (t == -1)) ? 1 : 0)