diff --git a/test/chunk_info.c b/test/chunk_info.c
index fba429f2b2b..a5dde34c5a7 100644
--- a/test/chunk_info.c
+++ b/test/chunk_info.c
@@ -2367,9 +2367,9 @@ test_chunk_address_with_userblock(hid_t fapl_id)
         int data    = -1;
         int data_ub = -1;
 
-        if (HDlseek(fd, (off_t)(od.addresses[i]), SEEK_SET) < 0)
+        if (HDlseek(fd, (HDoff_t)(od.addresses[i]), SEEK_SET) < 0)
             TEST_ERROR;
-        if (HDlseek(fd_ub, (off_t)(od_ub.addresses[i]), SEEK_SET) < 0)
+        if (HDlseek(fd_ub, (HDoff_t)(od_ub.addresses[i]), SEEK_SET) < 0)
             TEST_ERROR;
 
         if (HDread(fd, &data, sizeof(int)) != sizeof(int))
diff --git a/tools/src/h5jam/h5jam.c b/tools/src/h5jam/h5jam.c
index f311257e361..ffef472c9ba 100644
--- a/tools/src/h5jam/h5jam.c
+++ b/tools/src/h5jam/h5jam.c
@@ -162,7 +162,7 @@ main(int argc, char *argv[])
     hsize_t   startub;
     hsize_t   where;
     hsize_t   newubsize;
-    off_t     fsize;
+    HDoff_t   fsize;
     h5_stat_t sbuf;
     h5_stat_t sbuf2;
     int       res;
@@ -253,7 +253,7 @@ main(int argc, char *argv[])
         goto done;
     }
 
-    fsize = (off_t)sbuf.st_size;
+    fsize = (HDoff_t)sbuf.st_size;
 
     h5fid = HDopen(input_file, O_RDONLY);
     if (h5fid < 0) {
diff --git a/tools/src/h5jam/h5unjam.c b/tools/src/h5jam/h5unjam.c
index a93e85120b6..0ea5d494662 100644
--- a/tools/src/h5jam/h5unjam.c
+++ b/tools/src/h5jam/h5unjam.c
@@ -173,7 +173,7 @@ main(int argc, char *argv[])
 {
     hid_t     ifile = H5I_INVALID_HID;
     hid_t     plist = H5I_INVALID_HID;
-    off_t     fsize;
+    HDoff_t   fsize;
     hsize_t   usize;
     htri_t    testval;
     herr_t    status;
@@ -306,9 +306,9 @@ copy_to_file(FILE *infid, FILE *ofid, ssize_t _where, ssize_t show_much)
 {
     static char buf[COPY_BUF_SIZE];
     size_t      how_much;
-    off_t       where = (off_t)_where;
-    off_t       to;
-    off_t       from;
+    HDoff_t     where = (HDoff_t)_where;
+    HDoff_t     to;
+    HDoff_t     from;
     herr_t      ret_value = 0;
 
     /* nothing to copy */
@@ -349,8 +349,8 @@ copy_to_file(FILE *infid, FILE *ofid, ssize_t _where, ssize_t show_much)
 
         /* Update positions/size */
         how_much -= bytes_read;
-        from += (off_t)bytes_read;
-        to += (off_t)bytes_read;
+        from += (HDoff_t)bytes_read;
+        to += (HDoff_t)bytes_read;
 
         /* Write nchars bytes to output file */
         bytes_wrote = fwrite(buf, (size_t)1, bytes_read, ofid);