diff --git a/20/solution.c b/20/solution.c
index f222fad..4bcff0b 100644
--- a/20/solution.c
+++ b/20/solution.c
@@ -49,6 +49,8 @@ usage:
 
 
     fscanf(fp, "%ms", &algo);
+    for (char *ap=algo; *ap; ap++)
+        *ap = *ap == '#' ? 1 : 0;
 
     while (fscanf(fp, "%ms\n", &s) == 1) {
         size_t len = strlen(s);
@@ -96,7 +98,7 @@ usage:
                         else
                             v |= iter & 1;
 
-                        back[y * stride + x] = algo[v] == '#';
+                        back[y * stride + x] = algo[v];
                     }
                 }
             }