diff --git a/pan/tasks/task-xover.cc b/pan/tasks/task-xover.cc
@@ -172,8 +172,8 @@ void
 TaskXOver :: on_nntp_group (NNTP          * nntp,
                             const Quark   & group,
                             unsigned long   qty,
-                            unsigned long   low,
-                            unsigned long   high)
+                            uint64_t   low,
+                            uint64_t   high)
 {
   const Quark& servername (nntp->_server);
 
@@ -188,7 +188,7 @@ TaskXOver :: on_nntp_group (NNTP          * nntp,
          << " low " << low
          << " high " << high);
 
-  unsigned long l(low), h(high);
+  uint64_t l(low), h(high);
   _data.set_xover_low (group, nntp->_server, low);
   //std::cerr << LINE_ID << " This group's range is [" << low << "..." << high << ']' << std::endl;
 
@@ -200,7 +200,7 @@ TaskXOver :: on_nntp_group (NNTP          * nntp,
     l = std::max (low, high+1-_sample_size);
   }
   else { // NEW
-    unsigned long xh (_data.get_xover_high (group, nntp->_server));
+    uint64_t xh (_data.get_xover_high (group, nntp->_server));
     //std::cerr << LINE_ID << " current xover high is " << xh << std::endl;
     l = std::max (xh+1, low);
   }
@@ -211,7 +211,7 @@ TaskXOver :: on_nntp_group (NNTP          * nntp,
     add_steps (h-l);
     const int INCREMENT (1000);
     MiniTasks_t& minitasks (_server_to_minitasks[servername]);
-    for (unsigned long m=l; m<=h; m+=INCREMENT) {
+    for (uint64_t m=l; m<=h; m+=INCREMENT) {
       MiniTask mt (MiniTask::XOVER, m, m+INCREMENT);
       debug ("adding MiniTask for " << servername << ": xover [" << mt._low << '-' << mt._high << ']');
       minitasks.push_front (mt);
@@ -240,6 +240,19 @@ namespace
 
     return ul;
   }
+  uint64_t view_to_ull (const StringView& view)
+  {
+    uint64_t ul = 0ul;
+
+    if (!view.empty()) {
+      errno = 0;
+      ul = g_ascii_strtoull (view.str, 0, 10);
+      if (errno)
+        ul = 0ul;
+    }
+
+    return ul;
+  }
 
   bool header_is_nonencoded_utf8 (const StringView& in)
   {
@@ -260,10 +273,11 @@ TaskXOver :: on_nntp_line (NNTP               * nntp,
   _bytes_so_far += line.len;
 
   unsigned int lines=0u;
-  unsigned long number=0ul, bytes=0ul;
+  unsigned long bytes=0ul;
+  uint64_t number=0;
   StringView subj, author, date, mid, ref, tmp, xref, l(line);
   bool ok = !l.empty();
-  ok = ok && l.pop_token (tmp, '\t');    if (ok) number = view_to_ul (tmp);
+  ok = ok && l.pop_token (tmp, '\t');    if (ok) number = view_to_ull (tmp);
   ok = ok && l.pop_token (subj, '\t');   if (ok) subj.trim ();
   ok = ok && l.pop_token (author, '\t'); if (ok) author.trim ();
   ok = ok && l.pop_token (date, '\t');   if (ok) date.trim ();
@@ -291,10 +305,10 @@ TaskXOver :: on_nntp_line (NNTP               * nntp,
   // if news server doesn't provide an xref, fake one
   char * buf (0);
   if (xref.empty())
-    xref = buf = g_strdup_printf ("%s %s:%lu",
+    xref = buf = g_strdup_printf ("%s %s:%llu",
                        nntp->_server.c_str(), nntp->_group.c_str(), number);
 
-  unsigned long& h (_high[nntp->_server]);
+  uint64_t& h (_high[nntp->_server]);
   h = std::max (h, number);
 
   const char * fallback_charset = NULL; // FIXME
@@ -318,7 +332,7 @@ TaskXOver :: on_nntp_line (NNTP               * nntp,
     ++_articles_so_far;
 
   // emit a status update
-  int& prev = _last_xover_number[nntp];
+  uint64_t& prev = _last_xover_number[nntp];
   increment_step (number - prev);
   prev = number;
   if (!(_parts_so_far % 500))

diff --git a/pan/tasks/task-xover.h b/pan/tasks/task-xover.h
@@ -49,14 +49,14 @@ namespace pan
     private: // NNTP::Listener
       virtual void on_nntp_line (NNTP*, const StringView&);
       virtual void on_nntp_done (NNTP*, Health, const StringView&);
-      virtual void on_nntp_group (NNTP*, const Quark&, unsigned long, unsigned long, unsigned long);
+      virtual void on_nntp_group (NNTP*, const Quark&, unsigned long, uint64_t, uint64_t);
 
     private: // implementation - minitasks
       struct MiniTask {
         enum Type { GROUP, XOVER };
         Type _type;
-        unsigned long _low, _high;
-        MiniTask (Type type, unsigned long low=0ul, unsigned long high=0ul):
+        uint64_t _low, _high;
+        MiniTask (Type type, uint64_t low=0ul, uint64_t high=0ul):
           _type(type), _low(low), _high(high) {}
       };
       typedef std::deque<MiniTask> MiniTasks_t;
@@ -68,14 +68,14 @@ namespace pan
       const Quark _group;
       std::string _short_group_name;
       Mode _mode;
-      unsigned long _sample_size;
+      uint64_t _sample_size;
       time_t _days_cutoff;
       bool _group_xover_is_reffed;
-      typedef std::map<Quark,unsigned long> server_to_high_t;
+      typedef std::map<Quark,uint64_t> server_to_high_t;
       server_to_high_t _high;
       void update_work (bool subtract_one_from_nntp_count=false);
       std::set<Quark> _servers_that_got_xover_minitasks;
-      std::map<NNTP*,int> _last_xover_number;
+      std::map<NNTP*,uint64_t> _last_xover_number;
       unsigned long _bytes_so_far;
       unsigned long _parts_so_far;
       unsigned long _articles_so_far;

diff --git a/pan/usenet-utils/numbers.cc b/pan/usenet-utils/numbers.cc
@@ -19,9 +19,9 @@
 
 #include <config.h>
 #include <cctype>
+#include <algorithm>
 #include <pan/general/string-view.h>
 #include "numbers.h"
-#include <algorithm>
 
 using namespace pan;
 
@@ -36,7 +36,7 @@ namespace
    typedef Numbers::ranges_t::const_iterator r_cit;
 
    bool
-   maybe_merge_ranges (Numbers::ranges_t & ranges, int low)
+   maybe_merge_ranges (Numbers::ranges_t & ranges, uint64_t low)
    {
       bool merged = false;
 
@@ -59,15 +59,15 @@ namespace
 /**
  * @return the number of articles newly-marked as read 
  */
-unsigned long
+uint64_t
 Numbers :: mark_range (const Range& rr)
 {
-   int i;
-   unsigned long retval = 0;
+   uint64_t i;
+   uint64_t retval = 0;
    bool range_found = false;
-   int low_index (std::lower_bound (_marked.begin(), _marked.end(), rr.low)
+   uint64_t low_index (std::lower_bound (_marked.begin(), _marked.end(), rr.low)
                   - _marked.begin());
-   int high_index (std::lower_bound (_marked.begin(), _marked.end(), rr.high)
+   uint64_t high_index (std::lower_bound (_marked.begin(), _marked.end(), rr.high)
                    - _marked.begin());
 
    retval = rr.high + 1 - rr.low;
@@ -122,14 +122,14 @@ Numbers :: mark_range (const Range& rr)
    return retval;
 }
 
-unsigned long
+uint64_t
 Numbers :: unmark_range (const Range& ur)
 {
-   unsigned long retval = 0;
-   int i;
-   int low_index (std::lower_bound (_marked.begin(), _marked.end(), ur.low)
+   uint64_t retval = 0;
+   uint64_t i;
+   uint64_t low_index (std::lower_bound (_marked.begin(), _marked.end(), ur.low)
                   - _marked.begin());
-   int high_index (std::lower_bound (_marked.begin(), _marked.end(), ur.high)
+   uint64_t high_index (std::lower_bound (_marked.begin(), _marked.end(), ur.high)
                    - _marked.begin ());
 
    for (i=low_index; i<=high_index && i<(int)_marked.size(); )
@@ -172,17 +172,17 @@ Numbers :: unmark_range (const Range& ur)
 ******  MARK (PUBLIC)
 *****/
 
-unsigned long
-Numbers :: mark_range (unsigned long low, unsigned long high, bool add)
+uint64_t
+Numbers :: mark_range (uint64_t low, uint64_t high, bool add)
 {
    const Range r (low, high);
    return add ? mark_range(r) : unmark_range(r);
 }
 
 bool
-Numbers :: mark_one (unsigned long number, bool add)
+Numbers :: mark_one (uint64_t number, bool add)
 {
-   const unsigned long changed_qty (mark_range (number, number, add));
+   const uint64_t changed_qty (mark_range (number, number, add));
 
    if (add)
       return changed_qty==0;
@@ -201,8 +201,8 @@ Numbers :: mark_str (const StringView& str, bool add)
       phigh.pop_token (plow, '-');
       plow.trim ();
       phigh.trim ();
-      const unsigned long low (plow.empty() ? 0 : strtoul (plow.str, NULL, 10));
-      const unsigned long high (phigh.empty() ? low : strtoul (phigh.str, NULL, 10));
+      const uint64_t low (plow.empty() ? 0 : strtoul (plow.str, NULL, 10));
+      const uint64_t high (phigh.empty() ? low : strtoul (phigh.str, NULL, 10));
       mark_range (low, high, add);
    }
 }
@@ -218,7 +218,7 @@ Numbers :: clear ()
 *****/
 
 void
-Numbers :: clip (unsigned long low, unsigned long high)
+Numbers :: clip (uint64_t low, uint64_t high)
 {
    r_it it = std::lower_bound (_marked.begin(), _marked.end(), low);
    _marked.erase (_marked.begin(), it);
@@ -237,7 +237,7 @@ Numbers :: clip (unsigned long low, unsigned long high)
 *****/
 
 bool
-Numbers :: is_marked (unsigned long number) const
+Numbers :: is_marked (uint64_t number) const
 {
    r_cit it = std::lower_bound (_marked.begin(), _marked.end(), number);
 
@@ -262,11 +262,11 @@ Numbers :: to_string (std::string & str) const
    {
       Range r (*it);
 
-      snprintf (buf, sizeof(buf), "%lu", r.low);
+      snprintf (buf, sizeof(buf), "%llu", r.low);
       str += buf;
 
       if (r.low != r.high) {
-         snprintf (buf, sizeof(buf), "-%lu", r.high);
+         snprintf (buf, sizeof(buf), "-%llu", r.high);
          str += buf;
       }
 

diff --git a/pan/usenet-utils/numbers.h b/pan/usenet-utils/numbers.h
@@ -20,6 +20,7 @@
 #ifndef __Numbers_h__
 #define __Numbers_h__
 
+#include <stdint.h>
 #include <vector>
 #include <pan/general/string-view.h>
 
@@ -38,25 +39,25 @@ namespace pan
 
       /** Simple two-field struct defining a range. */
       struct Range {
-        unsigned long low;
-        unsigned long high;
+        uint64_t low;
+        uint64_t high;
         bool operator ==(const Range& that) const {
           return low==that.low && high==that.high;
         }
         Range (): low(0), high(0) {}
-        Range (unsigned long l, unsigned long h): low(l<h?l:h), high(h>l?h:l) {}
-        bool contains (unsigned long point) const {
+        Range (uint64_t l, uint64_t h): low(l<h?l:h), high(h>l?h:l) {}
+        bool contains (uint64_t point) const {
           return low<=point && point<=high;
         }
         bool contains (const Range& r) const {
           return low<=r.low && r.high<=high;
         }
-        int compare (unsigned long point) const {
+        int compare (uint64_t point) const {
           if (point < low) return -1;
           if (point > high) return 1;
           return 0;
         }
-        bool operator< (unsigned long point) const {
+        bool operator< (uint64_t point) const {
           return high < point;
         }
       };
@@ -65,8 +66,8 @@ namespace pan
 
     private:
       ranges_t _marked;
-      unsigned long mark_range (const Range&);
-      unsigned long unmark_range (const Range&);
+      uint64_t mark_range (const Range&);
+      uint64_t unmark_range (const Range&);
 
     public:
       bool operator== (const Numbers& that) const {
@@ -85,7 +86,7 @@ namespace pan
        * @param add true if we're adding the number, false if removing
        * @return the number's previous state in the set.
        */
-      bool mark_one (unsigned long number, bool add=true);
+      bool mark_one (uint64_t number, bool add=true);
 
       /**
        * Add or remove the specified range of numbers from the set.
@@ -96,7 +97,7 @@ namespace pan
        * @param add true if we're adding the numbers, false if removing
        * @return the quantity of numbers whose presence in the set changed.
        */
-      unsigned long mark_range (unsigned long low, unsigned long high, bool add=true);
+      uint64_t mark_range (uint64_t low, uint64_t high, bool add=true);
 
       /**
        * Mark numbers from a text string in to_str() and from_str() fromat.
@@ -108,7 +109,7 @@ namespace pan
       /**
        * @return true if the number is in this set, false otherwise
        */
-      bool is_marked (const unsigned long) const;
+      bool is_marked (const uint64_t) const;
 
       void clear ();
 
@@ -122,7 +123,7 @@ namespace pan
 
     public:
 
-      void clip (const unsigned long low, const unsigned long high);
+      void clip (const uint64_t low, const uint64_t high);
   };
 }