diff --git a/include/decl.h b/include/decl.h
index 82543e4ee..941b45a09 100644
--- a/include/decl.h
+++ b/include/decl.h
@@ -1056,6 +1056,7 @@ struct instance_globals {
 
     /* o_init.c */
     short disco[NUM_OBJECTS];
+    short oclass_prob_totals[MAXOCLASSES];
 
     /* objname.c */
     /* distantname used by distant_name() to pass extra information to
diff --git a/include/extern.h b/include/extern.h
index 3305405b6..6bf82cd25 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -1741,6 +1741,7 @@ extern void consoletty_exit(void);
 /* ### o_init.c ### */
 
 extern void init_objects(void);
+extern void init_oclass_probs(void);
 extern void obj_shuffle_range(int, int *, int *);
 extern int find_skates(void);
 extern boolean objdescr_is(struct obj *, const char *);
diff --git a/include/objects.h b/include/objects.h
index ba95a626a..7018417d3 100644
--- a/include/objects.h
+++ b/include/objects.h
@@ -651,7 +651,7 @@ BOOTS("levitation boots", "snow boots",
     OBJECT(OBJ(name, stone),                                          \
            BITS(0, 0, spec, 0, mgc, spec, 0, 0, 0,                    \
                 HARDGEM(mohs), 0, P_NONE, metal),                     \
-           power, RING_CLASS, 0, 0, 3, cost, 0, 0, 0, 0, 15, color,sn)
+           power, RING_CLASS, 1, 0, 3, cost, 0, 0, 0, 0, 15, color,sn)
 RING("adornment", "wooden",
      ADORNED,                  100, 1, 1, 2, WOOD, HI_WOOD, RIN_ADORNMENT),
 RING("gain strength", "granite",
diff --git a/src/decl.c b/src/decl.c
index 796079961..3a7ee43f3 100644
--- a/src/decl.c
+++ b/src/decl.c
@@ -528,6 +528,7 @@ const struct instance_globals g_init = {
 
     /* o_init.c */
     DUMMY, /* disco */
+    DUMMY, /* oclass_prob_totals */
 
     /* objname.c */
     0, /* distantname */
diff --git a/src/mkobj.c b/src/mkobj.c
index c2cd6a652..6d7902b7f 100644
--- a/src/mkobj.c
+++ b/src/mkobj.c
@@ -206,7 +206,7 @@ mksobj_migr_to_species(
 struct obj *
 mkobj(int oclass, boolean artif)
 {
-    int tprob, i, prob = rnd(1000);
+    int tprob, i, prob;
 
     if (oclass == RANDOM_CLASS) {
         const struct icp *iprobs = Is_rogue_level(&u.uz)
@@ -223,13 +223,16 @@ mkobj(int oclass, boolean artif)
         i = rnd_class(g.bases[SPBOOK_CLASS], SPE_BLANK_PAPER);
         oclass = SPBOOK_CLASS; /* for sanity check below */
     } else {
+        prob = rnd(g.oclass_prob_totals[oclass]);
         i = g.bases[oclass];
         while ((prob -= objects[i].oc_prob) > 0)
             ++i;
     }
 
-    if (objects[i].oc_class != oclass || !OBJ_NAME(objects[i]))
-        panic("probtype error, oclass=%d i=%d", (int) oclass, i);
+    if (objects[i].oc_class != oclass || !OBJ_NAME(objects[i])) {
+        impossible("probtype error, oclass=%d i=%d", (int) oclass, i);
+        i = g.bases[oclass];
+    }
 
     return mksobj(i, TRUE, artif);
 }
diff --git a/src/o_init.c b/src/o_init.c
index 22dcab445..ef1fd6036 100644
--- a/src/o_init.c
+++ b/src/o_init.c
@@ -42,7 +42,7 @@ shuffle_tiles(void)
 static void
 setgemprobs(d_level* dlev)
 {
-    int j, first, lev;
+    int j, first, lev, sum = 0;
 
     if (dlev)
         lev = (ledger_no(dlev) > maxledgerno()) ? maxledgerno()
@@ -62,6 +62,11 @@ setgemprobs(d_level* dlev)
     }
     for (j = first; j <= LAST_GEM; j++)
         objects[j].oc_prob = (171 + j - first) / (LAST_GEM + 1 - first);
+
+    /* recompute GEM_CLASS total oc_prob - including rocks/stones */
+    for (j = g.bases[GEM_CLASS]; j < g.bases[GEM_CLASS + 1]; j++)
+        sum += objects[j].oc_prob;
+    g.oclass_prob_totals[GEM_CLASS] = sum;
 }
 
 /* shuffle descriptions on objects o_low to o_high */
@@ -106,7 +111,7 @@ shuffle(int o_low, int o_high, boolean domaterial)
 void
 init_objects(void)
 {
-    int i, first, last, sum, prevoclass;
+    int i, first, last, prevoclass;
     char oclass;
 #ifdef TEXTCOLOR
 #define COPY_OBJ_DESCR(o_dst, o_src) \
@@ -167,17 +172,6 @@ init_objects(void)
                 break;
             }
         }
- checkprob:
-        sum = 0;
-        for (i = first; i < last; i++)
-            sum += objects[i].oc_prob;
-        if (sum == 0) {
-            for (i = first; i < last; i++)
-                objects[i].oc_prob = (1000 + i - first) / (last - first);
-            goto checkprob;
-        }
-        if (sum != 1000)
-            error("init-prob error for class %d (%d%%)", oclass, sum);
         first = last;
         prevoclass = (int) oclass;
     }
@@ -207,6 +201,8 @@ init_objects(void)
             objects[i].oc_name_known = nmkn ? 0 : 1;
         }
     }
+    /* compute oclass_prob_totals */
+    init_oclass_probs();
 
     /* shuffle descriptions */
     shuffle_all();
@@ -216,6 +212,33 @@ init_objects(void)
     objects[WAN_NOTHING].oc_dir = rn2(2) ? NODIR : IMMEDIATE;
 }
 
+/* Compute the total probability of each object class.
+ * Assumes g.bases[] has already been set. */
+void
+init_oclass_probs(void)
+{
+    int i;
+    short sum;
+    int oclass;
+    for (oclass = 0; oclass < MAXOCLASSES; ++oclass) {
+        sum = 0;
+        for (i = g.bases[oclass]; i < g.bases[oclass + 1]; ++i) {
+            sum += objects[i].oc_prob;
+        }
+        if (sum <= 0 && oclass != ILLOBJ_CLASS
+            && g.bases[oclass] != g.bases[oclass + 1]) {
+            impossible("zero or negative probability total for oclass %d",
+                       oclass);
+            /* gracefully fail by setting all members of this class to 1 */
+            for (i = g.bases[oclass]; i < g.bases[oclass + 1]; ++i) {
+                objects[i].oc_prob = 1;
+                sum++;
+            }
+        }
+        g.oclass_prob_totals[oclass] = sum;
+    }
+}
+
 /* retrieve the range of objects that otyp shares descriptions with */
 void
 obj_shuffle_range(
diff --git a/src/restore.c b/src/restore.c
index 1afa82693..ddabdab32 100644
--- a/src/restore.c
+++ b/src/restore.c
@@ -527,7 +527,7 @@ restgamestate(NHFILE* nhfp, unsigned int* stuckid, unsigned int* steedid)
 
     if (nhfp->structlevel)
         mread(nhfp->fd, (genericptr_t) &uid, sizeof uid);
-      
+
     if (SYSOPT_CHECK_SAVE_UID
         && uid != (unsigned long) getuid()) { /* strange ... */
         /* for wizard mode, issue a reminder; for others, treat it
@@ -582,7 +582,7 @@ restgamestate(NHFILE* nhfp, unsigned int* stuckid, unsigned int* steedid)
     if (nhfp->structlevel)
         mread(nhfp->fd, (genericptr_t) &u, sizeof(struct you));
     g.youmonst.cham = u.mcham;
-        
+
     if (nhfp->structlevel)
         mread(nhfp->fd, (genericptr_t) timebuf, 14);
     timebuf[14] = '\0';
@@ -692,7 +692,7 @@ restgamestate(NHFILE* nhfp, unsigned int* stuckid, unsigned int* steedid)
     }
     freefruitchn(g.ffruit); /* clean up fruit(s) made by initoptions() */
     g.ffruit = loadfruitchn(nhfp);
-  
+
     restnames(nhfp);
     restore_waterlevel(nhfp);
     restore_msghistory(nhfp);
@@ -857,6 +857,7 @@ dorecover(NHFILE* nhfp)
     substitute_tiles(&u.uz);
 #endif
     max_rank_sz(); /* to recompute g.mrank_sz (botl.c) */
+    init_oclass_probs(); /* recompute g.oclass_prob_totals[] */
     /* take care of iron ball & chain */
     for (otmp = fobj; otmp; otmp = otmp->nobj)
         if (otmp->owornmask)
@@ -1078,7 +1079,7 @@ getlev(NHFILE* nhfp, int pid, xchar lev)
         g.doorindex = g.rooms[g.nroom - 1].fdoor + g.rooms[g.nroom - 1].doorct;
     else
         g.doorindex = 0;
-  
+
     restore_timers(nhfp, RANGE_LEVEL, elapsed);
     restore_light_sources(nhfp);
     fmon = restmonchn(nhfp);