diff --git a/src/plugins/streamers/oasis/db_plugin/dbOASISReader.cc b/src/plugins/streamers/oasis/db_plugin/dbOASISReader.cc
index d7945d262..91c5d000e 100644
--- a/src/plugins/streamers/oasis/db_plugin/dbOASISReader.cc
+++ b/src/plugins/streamers/oasis/db_plugin/dbOASISReader.cc
@@ -204,7 +204,7 @@ void
 OASISReader::get_str (std::string &s)
 {
   size_t l = 0;
-  get (l);
+  get_size (l);
 
   char *b = (char *) m_stream.get (l);
   if (b) {
@@ -535,31 +535,31 @@ OASISReader::read_offset_table ()
   uint64_t of = 0;
 
   of = get_uint64 ();
-  get (m_table_cellname);
+  get_size (m_table_cellname);
   if (m_table_cellname != 0 && m_expect_strict_mode >= 0 && ((of == 0) != (m_expect_strict_mode == 0))) {
     warn (tl::to_string (tr ("CELLNAME offset table has unexpected strict mode")));
   }
 
   of = get_uint64 ();
-  get (m_table_textstring);
+  get_size (m_table_textstring);
   if (m_table_textstring != 0 && m_expect_strict_mode >= 0 && ((of == 0) != (m_expect_strict_mode == 0))) {
     warn (tl::to_string (tr ("TEXTSTRING offset table has unexpected strict mode")));
   }
 
   of = get_uint64 ();
-  get (m_table_propname);
+  get_size (m_table_propname);
   if (m_table_propname != 0 && m_expect_strict_mode >= 0 && ((of == 0) != (m_expect_strict_mode == 0))) {
     warn (tl::to_string (tr ("PROPNAME offset table has unexpected strict mode")));
   }
 
   of = get_uint64 ();
-  get (m_table_propstring);
+  get_size (m_table_propstring);
   if (m_table_propstring != 0 && m_expect_strict_mode >= 0 && ((of == 0) != (m_expect_strict_mode == 0))) {
     warn (tl::to_string (tr ("PROPSTRING offset table has unexpected strict mode")));
   }
 
   of = get_uint64 ();
-  get (m_table_layername);
+  get_size (m_table_layername);
   if (m_table_layername != 0 && m_expect_strict_mode >= 0 && ((of == 0) != (m_expect_strict_mode == 0))) {
     warn (tl::to_string (tr ("LAYERNAME offset table has unexpected strict mode")));
   }
@@ -567,7 +567,7 @@ OASISReader::read_offset_table ()
   //  XNAME table ignored currently
   get_uint64 ();
   size_t dummy = 0;
-  get (dummy);
+  get_size (dummy);
 }
 
 static const char magic_bytes[] = { "%SEMI-OASIS\015\012" };
@@ -1003,7 +1003,7 @@ OASISReader::do_read (db::Layout &layout)
         error (tl::sprintf (tl::to_string (tr ("Invalid CBLOCK compression type %d")), type));
       }
 
-      size_t dummy = 0;
+      uint64_t dummy = 0;
       get (dummy);  // uncomp-byte-count - not needed
       get (dummy);  // comp-byte-count - not needed
 
@@ -1452,7 +1452,7 @@ OASISReader::read_element_properties (bool ignore_special)
         error (tl::sprintf (tl::to_string (tr ("Invalid CBLOCK compression type %d")), type));
       }
 
-      size_t dummy = 0;
+      uint64_t dummy = 0;
       get (dummy);  // uncomp-byte-count - not needed
       get (dummy);  // comp-byte-count - not needed
 
@@ -3557,7 +3557,7 @@ OASISReader::do_read_cell (db::cell_index_type cell_index, db::Layout &layout)
         error (tl::sprintf (tl::to_string (tr ("Invalid CBLOCK compression type %d")), type));
       }
 
-      size_t dummy = 0;
+      uint64_t dummy = 0;
       get (dummy);  // uncomp-byte-count - not needed
       get (dummy);  // comp-byte-count - not needed
 
diff --git a/src/plugins/streamers/oasis/db_plugin/dbOASISReader.h b/src/plugins/streamers/oasis/db_plugin/dbOASISReader.h
index 06baab382..28df204fc 100644
--- a/src/plugins/streamers/oasis/db_plugin/dbOASISReader.h
+++ b/src/plugins/streamers/oasis/db_plugin/dbOASISReader.h
@@ -245,6 +245,11 @@ private:
     l = get_int64 ();
   }
 
+  void get_size (size_t &l)
+  {
+    l = get_uint64 ();
+  }
+
   void get (uint64_t &l)
   {
     l = get_uint64 ();
diff --git a/src/plugins/streamers/oasis/db_plugin/dbOASISWriter.cc b/src/plugins/streamers/oasis/db_plugin/dbOASISWriter.cc
index 5a613115c..4090afe01 100644
--- a/src/plugins/streamers/oasis/db_plugin/dbOASISWriter.cc
+++ b/src/plugins/streamers/oasis/db_plugin/dbOASISWriter.cc
@@ -820,7 +820,7 @@ void
 OASISWriter::write_bstring (const char *s)
 {
   size_t l = strlen (s);
-  write (l);
+  write ((uint64_t) l);
   write_bytes (s, l);
 }
 
@@ -839,7 +839,7 @@ void
 OASISWriter::write_astring (const char *s)
 {
   std::string nstr = make_astring (s);
-  write (nstr.size ());
+  write ((uint64_t) nstr.size ());
   write_bytes (nstr.c_str (), nstr.size ());
 }
 
@@ -858,7 +858,7 @@ void
 OASISWriter::write_nstring (const char *s)
 {
   std::string nstr = make_nstring (s);
-  write (nstr.size ());
+  write ((uint64_t) nstr.size ());
   write_bytes (nstr.c_str (), nstr.size ());
 }
 
@@ -1062,8 +1062,8 @@ OASISWriter::end_cblock ()
     //  RFC1951 compression:
     write_byte (0); 
 
-    write (m_cblock_buffer.size ());
-    write (m_cblock_compressed.size ());
+    write ((uint64_t) m_cblock_buffer.size ());
+    write ((uint64_t) m_cblock_compressed.size ());
 
     write_bytes (m_cblock_compressed.data (), m_cblock_compressed.size ());
 
@@ -1767,23 +1767,23 @@ OASISWriter::write (db::Layout &layout, tl::OutputStream &stream, const db::Save
 
     //  cellnames
     write_byte (1); 
-    write (cellnames_table_pos);
+    write ((uint64_t) cellnames_table_pos);
 
     //  textstrings
     write_byte (1); 
-    write (textstrings_table_pos);
+    write ((uint64_t) textstrings_table_pos);
 
     //  propnames
     write_byte (1); 
-    write (propnames_table_pos);
+    write ((uint64_t) propnames_table_pos);
 
     //  propstrings
     write_byte (1); 
-    write (propstrings_table_pos);
+    write ((uint64_t) propstrings_table_pos);
 
     //  layernames
     write_byte (1); 
-    write (layernames_table_pos);
+    write ((uint64_t) layernames_table_pos);
 
     //  xnames (not used)
     write_byte (1); 
@@ -1847,11 +1847,11 @@ OASISWriter::write (const Repetition &rep)
 
       if (g <= 1) {
         write_byte (10);
-        write (iterated->size () - 1);
+        write ((uint64_t) iterated->size () - 1);
         g = 1;
       } else {
         write_byte (11);
-        write (iterated->size () - 1);
+        write ((uint64_t) iterated->size () - 1);
         write_ucoord (g, 1.0);
       }
 
@@ -1881,31 +1881,31 @@ OASISWriter::write (const Repetition &rep)
 
         if (b.x () == 0 && b.y () >= 0) {
           write_byte (3);
-          write (bmax - 2);
+          write ((uint64_t) bmax - 2);
           write_ucoord (b.y ());
         } else if (b.y () == 0 && b.x () >= 0) {
           write_byte (2);
-          write (bmax - 2);
+          write ((uint64_t) bmax - 2);
           write_ucoord (b.x ());
         } else {
           write_byte (9);
-          write (bmax - 2);
+          write ((uint64_t) bmax - 2);
           write_gdelta (b);
         }
 
       } else if (b.x () == 0 && b.y () >= 0 && a.y () == 0 && a.x () >= 0) {
 
         write_byte (1);
-        write (amax - 2);
-        write (bmax - 2);
+        write ((uint64_t) amax - 2);
+        write ((uint64_t) bmax - 2);
         write_ucoord (a.x ());
         write_ucoord (b.y ());
 
       } else if (b.y () == 0 && b.x () >= 0 && a.x () == 0 && a.y () >= 0) {
 
         write_byte (1);
-        write (bmax - 2);
-        write (amax - 2);
+        write ((uint64_t) bmax - 2);
+        write ((uint64_t) amax - 2);
         write_ucoord (b.x ());
         write_ucoord (a.y ());