diff -r 024dfd95ee84 -r 5fdf351e41e1 src/mem/dram_ctrl.cc
--- a/src/mem/dram_ctrl.cc	Thu Apr 09 16:28:19 2015 -0400
+++ b/src/mem/dram_ctrl.cc	Thu Apr 09 16:40:59 2015 -0400
@@ -538,11 +538,14 @@
                     // update both the address and the size
                     (*w)->addr = addr;
                     (*w)->size = size;
-                } else if ((addr + size) >= (*w)->addr &&
-                           ((*w)->addr + (*w)->size - addr) <= burstSize) {
+                } else if ((addr + size) > (*w)->addr ||
+                    ((addr + size) == (*w)->addr &&
+                     ((*w)->addr & (burstSize - 1)) != 0)) {
                     // the new one is just before or partially
-                    // overlapping with the existing one, and together
-                    // they fit within a burst
+                    // overlapping with the existing one within a burst boundary
+                    // are merged together.
+                    // assert that together they fit within a burst
+                    assert(((*w)->addr + (*w)->size - addr) <= burstSize);
                     DPRINTF(DRAM, "Merging write before existing burst\n");
                     merged = true;
                     // the existing queue item needs to be adjusted with
@@ -560,11 +563,13 @@
                     DPRINTF(DRAM, "Merging write into existing burst\n");
                     merged = true;
                     // no adjustments necessary
-                } else if (((*w)->addr + (*w)->size) >= addr &&
-                           (addr + size - (*w)->addr) <= burstSize) {
+                } else if (((*w)->addr + (*w)->size) > addr ||
+                           (((*w)->addr + (*w)->size) == addr &&
+                           (addr & (burstSize - 1)) != 0)) {
                     // the existing one is just before or partially
-                    // overlapping with the new one, and together
-                    // they fit within a burst
+                    // overlapping with the new one within a burst boundary
+                    // assert that they fit within a burst
+                    assert((addr + size - (*w)->addr <= burstSize));
                     DPRINTF(DRAM, "Merging write after existing burst\n");
                     merged = true;
                     // the address is right, and only the size has