--- netpbm-10.35/converter/pbm/pbmtog3.c.pbmtog3segfault	2006-09-18 12:20:32.000000000 +0200
+++ netpbm-10.35/converter/pbm/pbmtog3.c	2006-12-28 11:43:19.000000000 +0100
@@ -371,7 +371,7 @@
                 r2 <<= c++; r2 <<= 1;  k += c; 
             } 
         }
-        if (milepost[n - 1] != cols) 
+        if (!n || milepost[n - 1] != cols) 
             milepost[n++] = cols;
         *lengthP = n;
     }