diff --git a/src/main/java/puzzle/SwedishGenerator.java b/src/main/java/puzzle/SwedishGenerator.java
index 19bdbb1..bba262e 100644
--- a/src/main/java/puzzle/SwedishGenerator.java
+++ b/src/main/java/puzzle/SwedishGenerator.java
@@ -285,12 +285,36 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
       static int offset(int r, int c) { return r | (c << 3); }
       /// the pos will never target a clue
       public byte letter32At(int pos) { return g[pos]; }
-      void setLetter(int idx, byte ch)  { g[idx] = ch; }
+      void setLetterLo(int idx, byte ch) {
+         lo &= ~(1L << idx);
+         
+         g[idx] = ch;
+      }
+      void setLetterHi(int idx, byte ch) {
+         hi &= ~(1L << idx & 63);
+         
+         g[idx] = ch;
+      }
+      void setLetter(int idx, byte ch) {
+         if ((idx & 64)==0)
+            setLetterLo(idx, ch);
+         else
+            setLetterHi(idx, ch);
+      }
       
-      private void clearletter(int idx) { g[idx] = DASH; }
+      private void clearletterLo(int idx) {
+         g[idx] = DASH;
+         
+         lo |= (1L << idx);
+      }
+      private void clearletterHi(int idx) {
+         g[idx] = DASH;
+         
+         hi |= (1L << idx & 63);
+      }
       void undoPlace(long maskLo, long maskHi) {
-         for (long b = maskLo; b != 0; b &= b - 1) clearletter(Long.numberOfTrailingZeros(b));
-         for (long b = maskHi; b != 0; b &= b - 1) clearletter(64 | Long.numberOfTrailingZeros(b));
+         for (long b = maskLo; b != 0; b &= b - 1) clearletterLo(Long.numberOfTrailingZeros(b));
+         for (long b = maskHi; b != 0; b &= b - 1) clearletterHi(64 | Long.numberOfTrailingZeros(b));
       }
    }
    
@@ -723,24 +747,24 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
    }
    
    static long patternForSlot(Grid grid, Slot s) {
-      /*if ((s.lo & ~grid.lo) == 0 && (s.hi & ~grid.hi) == 0) {
+     if ((s.lo & ~grid.lo) == 0 && (s.hi & ~grid.hi) == 0) {
          return 0;
-      }*/
+      }
       long p = 0;
       if (s.increasing()) {
          for (long b = s.lo & ~grid.lo; b != 0; b &= b - 1) {
-            int idx = Long.numberOfTrailingZeros(b);
-            int val = grid.g[idx];
-            if (val != 0) {
+            int  idx = Long.numberOfTrailingZeros(b);
+            byte val = grid.g[idx];
+            if (val != DASH) {
                int i = Long.bitCount(s.lo & ((1L << idx) - 1));
                p |= ((long) (i * 26 + val)) << (i << 3);
             }
          }
          int offset = Long.bitCount(s.lo);
          for (long b = s.hi & ~grid.hi; b != 0; b &= b - 1) {
-            int idx = Long.numberOfTrailingZeros(b);
-            int val = grid.g[64 | idx];
-            if (val != 0) {
+            int  idx = Long.numberOfTrailingZeros(b);
+            byte val = grid.g[64 | idx];
+            if (val != DASH) {
                int i = offset + Long.bitCount(s.hi & ((1L << idx) - 1));
                p |= ((long) (i * 26 + val)) << (i << 3);
             }
@@ -748,17 +772,17 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
       } else {
          int offset = Long.bitCount(s.hi);
          for (long b = s.hi & ~grid.hi; b != 0; b &= b - 1) {
-            int idx = Long.numberOfTrailingZeros(b);
-            int val = grid.g[64 | idx];
-            if (val != 0) {
+            int  idx = Long.numberOfTrailingZeros(b);
+            byte val = grid.g[64 | idx];
+            if (val != DASH) {
                int i = Long.bitCount(s.hi & ~((1L << idx) | ((1L << idx) - 1)));
                p |= ((long) (i * 26 + val)) << (i << 3);
             }
          }
          for (long b = s.lo & ~grid.lo; b != 0; b &= b - 1) {
-            int idx = Long.numberOfTrailingZeros(b);
-            int val = grid.g[idx];
-            if (val != 0) {
+            int  idx = Long.numberOfTrailingZeros(b);
+            byte val = grid.g[idx];
+            if (val != DASH) {
                int i = offset + Long.bitCount(s.lo & ~((1L << idx) | ((1L << idx) - 1)));
                p |= ((long) (i * 26 + val)) << (i << 3);
             }
@@ -781,7 +805,7 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
             byte cur = grid.letter32At(idx), ch = Lemma.byteAt(w, i);
             if (cur == DASH) {
                maskLo |= (1L << idx);
-               grid.setLetter(idx, ch);
+               grid.setLetterLo(idx, ch);
             } else if (cur != ch) {
                grid.undoPlace(maskLo, maskHi);
                return false;
@@ -792,7 +816,7 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
             byte cur = grid.letter32At(idx), ch = Lemma.byteAt(w, i);
             if (cur == DASH) {
                maskHi |= (1L << (idx & 63));
-               grid.setLetter(idx, ch);
+               grid.setLetterHi(idx, ch);
             } else if (cur != ch) {
                grid.undoPlace(maskLo, maskHi);
                return false;
@@ -805,7 +829,7 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
             byte cur = grid.letter32At(idx), ch = Lemma.byteAt(w, i);
             if (cur == DASH) {
                maskHi |= (1L << msb);
-               grid.setLetter(idx, ch);
+               grid.setLetterHi(idx, ch);
             } else if (cur != ch) {
                grid.undoPlace(maskLo, maskHi);
                return false;
@@ -818,7 +842,7 @@ public record SwedishGenerator(Rng rng, int[] stack, Clues cache) {
             byte cur = grid.letter32At(idx), ch = Lemma.byteAt(w, i);
             if (cur == DASH) {
                maskLo |= (1L << msb);
-               grid.setLetter(idx, ch);
+               grid.setLetterLo(idx, ch);
             } else if (cur != ch) {
                grid.undoPlace(maskLo, maskHi);
                return false;