diff --git a/finders.c b/finders.c
index 5bbcf37..92e5116 100644
--- a/finders.c
+++ b/finders.c
@@ -4682,8 +4682,6 @@ int getParaRange(const DoublePerlinNoise *para, double *pmin, double *pmax,
     }
 
     //(*(double*)data) = -1e9+1; // testing
-    if (lmin == lmax)
-        return 0;
 
     step = (int) (1.0 / (perlin_grad * lmax + FLT_EPSILON)) + 1;
 
diff --git a/layers.h b/layers.h
index 54a8ffd..d3b1e65 100644
--- a/layers.h
+++ b/layers.h
@@ -547,6 +547,8 @@ int p2overworld(int mc, const uint64_t np[6], uint64_t *dat);
  * Initialize BiomeNoise for only a single climate parameter.
  * If nptype == NP_DEPTH, the value is sampled at y=0. Note that this value
  * changes linearly with the height (i.e. -= y/128).
+ * A maximum of nmax octaves is set, initializing only the most contributing
+ * octaves up to that point. Use -1 for a full initialization.
  */
 void setClimateParaSeed(BiomeNoise *bn, uint64_t seed, int large, int nptype, int nmax);
 double sampleClimatePara(const BiomeNoise *bn, int64_t *np, double x, double z);
diff --git a/quadbase.c b/quadbase.c
index db0eba7..22735c7 100644
--- a/quadbase.c
+++ b/quadbase.c
@@ -213,11 +213,15 @@ STRUCT(threadinfo_t)
     const uint64_t *lowBits;
     int lowBitCnt;
     int lowBitN;
+    char skipStart;
 
     // testing function
     int (*check)(uint64_t, void*);
     void *data;
 
+    // abort check
+    volatile char *stop;
+
     // output
     char path[MAX_PATHLEN];
     FILE *fp;
@@ -288,7 +292,8 @@ static DWORD WINAPI searchAll48Thread(LPVOID data)
         {
             if unlikely(info->check(seed, info->data))
             {
-                if (info->fp)
+                if (seed == info->start && info->skipStart) {} // skip
+                else if (info->fp)
                 {
                     fprintf(info->fp, "%" PRId64"\n", (int64_t)seed);
                     fflush(info->fp);
@@ -316,6 +321,8 @@ static DWORD WINAPI searchAll48Thread(LPVOID data)
             {
                 idx = 0;
                 mid += hstep;
+                if (info->stop && *info->stop)
+                    break;
             }
 
             seed = mid | info->lowBits[idx];
@@ -327,7 +334,8 @@ static DWORD WINAPI searchAll48Thread(LPVOID data)
         {
             if unlikely(info->check(seed, info->data))
             {
-                if (info->fp)
+                if (seed == info->start && info->skipStart) {} // skip
+                else if (info->fp)
                 {
                     fprintf(info->fp, "%" PRId64"\n", (int64_t)seed);
                     fflush(info->fp);
@@ -350,6 +358,8 @@ static DWORD WINAPI searchAll48Thread(LPVOID data)
                 }
             }
             seed++;
+            if ((seed & 0xfff) == 0 && info->stop && *info->stop)
+                break;
         }
     }
 
@@ -369,7 +379,8 @@ int searchAll48(
         int                 lowBitCnt,
         int                 lowBitN,
         int (*check)(uint64_t s48, void *data),
-        void *              data
+        void *              data,
+        volatile char *     stop
         )
 {
     threadinfo_t *info = (threadinfo_t*) malloc(threads* sizeof(*info));
@@ -412,8 +423,10 @@ int searchAll48(
         info[t].lowBits = lowBits;
         info[t].lowBitCnt = lowBitCnt;
         info[t].lowBitN = lowBitN;
+        info[t].skipStart = 0;
         info[t].check = check;
         info[t].data = data;
+        info[t].stop = stop;
 
         if (path)
         {
@@ -442,6 +455,7 @@ int searchAll48(
                 if (sscanf(buf, "%" PRId64, &lentry) == 1)
                 {
                     info[t].start = lentry;
+                    info[t].skipStart = 1;
                     printf("Continuing thread %d at seed %" PRId64 "\n",
                         t, lentry);
                 }
@@ -483,6 +497,9 @@ int searchAll48(
 
 #endif
 
+    if (stop && *stop)
+        goto L_err;
+
     if (path)
     {
         // merge partial files
diff --git a/quadbase.h b/quadbase.h
index ade1a58..1fa2420 100644
--- a/quadbase.h
+++ b/quadbase.h
@@ -148,7 +148,8 @@ float isQuadBaseLarge (const StructureConfig sconf, uint64_t seed,
  * @lowBitCnt   length of lower bit subset
  * @lowBitN     number of bits in the subset values
  * @check       the testing function, should return non-zero for desired seeds
- * @data        custon data argument passed to 'check'
+ * @data        custom data argument passed to 'check'
+ * @stop        occasional check for abort (nullable)
  *
  * Returns zero upon success.
  */
@@ -161,7 +162,8 @@ int searchAll48(
         int                 lowBitCnt,
         int                 lowBitN,
         int (*check)(uint64_t s48, void *data),
-        void *              data
+        void *              data,
+        volatile char *     stop // should be atomic, but is fine as stop flag
         );
 
 /* Finds the optimal AFK location for four structures of size (ax,ay,az),