diff --git a/NEWS b/NEWS
index e5af5c2cf3e2cdf128dc61b30e0c315878df2d71..500ed9dee1342b786c124a759e9dcff0ab1321ea 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,8 @@ documents those changes that are of interest to users and admins.
     line.  Previously the line could be shortened prematurely.
  -- BLUEGENE - Fix to make sure we don't erroneously set a connection type
     to SMALL.
+ -- Type cast a negative uint64_t to int64_t to avoid confusion when doing 
+    arithmetic with it in accounting dealing with over commit time.
 
 * Changes in SLURM 2.0.8
 ========================
diff --git a/src/plugins/accounting_storage/mysql/mysql_rollup.c b/src/plugins/accounting_storage/mysql/mysql_rollup.c
index eadc0e1a348e120bfe68574f836510f62d2dbf81..ff3654b68f222f415b1c44c4ea6555f5355d5908 100644
--- a/src/plugins/accounting_storage/mysql/mysql_rollup.c
+++ b/src/plugins/accounting_storage/mysql/mysql_rollup.c
@@ -804,8 +804,8 @@ extern int mysql_hourly_rollup(mysql_conn_t *mysql_conn,
 			if((int64_t)c_usage->i_cpu < 0) {
 /* 				info("got %d %d %d", c_usage->r_cpu, */
 /* 				     c_usage->i_cpu, c_usage->o_cpu); */
-				c_usage->r_cpu += c_usage->i_cpu;
-				c_usage->o_cpu -= c_usage->i_cpu;
+				c_usage->r_cpu += (int64_t)c_usage->i_cpu;
+				c_usage->o_cpu -= (int64_t)c_usage->i_cpu;
 				c_usage->i_cpu = 0;
 				if((int64_t)c_usage->r_cpu < 0)
 					c_usage->r_cpu = 0;