bugs in transitive reduction?

thickenings.c

@@ -12,6 +12,12 @@
 
 char *alphabetize(int *word, int len, const char *alphabet, char *buffer)
 {
+  if(len == 0) {
+    buffer[0] = '1';
+    buffer[1] = 0;
+    return buffer;
+  }
+
   int i = 0;
   for(i = 0; i < len; i++)
     buffer[i] = alphabet[word[i]];