Index: lib/libc/tests/stdlib/mergesort_test.c
===================================================================
--- lib/libc/tests/stdlib/mergesort_test.c
+++ lib/libc/tests/stdlib/mergesort_test.c
@@ -51,12 +51,15 @@
  * Test from 2^BASE_EXP to 2^MAX_EXP elements of type SORT_TYPE
  */
 #define BASE_EXP 10
-#define MAX_EXP  15
+#define MAX_EXP  18
 #define SORT_TYPE int
 
 // Number of chars in the odd elt subarray
 #define NCHARS 5
 
+// Canary value to verify buffer is intact
+#define CANARY 0XDEADBEEF
+
 #define check_array_eq(it, len, expected, actual) do { \
     for (it = 0; it < len; it++) \
         ATF_CHECK_MSG( \
@@ -410,12 +413,16 @@
 	struct big sresvector[IVEC_LEN];
 	struct big testvector[IVEC_LEN];
 	int i, j;
+	size_t size = SPACE_LEN * sizeof(int);
 
 	for (j = 2; j < IVEC_LEN; j++) {
 		/* Populate test vectors */
-		for (i = 0; i < j; i++)
+		for (i = 0; i < j; i++) {
 			testvector[i].value = sresvector[i].value =
 			    initvector[i];
+			memset(testvector[i].spacetaker, CANARY, size);
+			memset(sresvector[i].spacetaker, CANARY, size);
+		}
 
 		/* Sort using mergesort(3) */
 		mergesort(testvector, j, sizeof(testvector[0]), bigsorthelp);
@@ -424,11 +431,15 @@
 		    bigsorthelp);
 
 		/* Compare results */
-		for (i = 0; i < j; i++)
+		for (i = 0; i < j; i++) {
 			ATF_CHECK_MSG(testvector[i].value ==
 			    sresvector[i].value,
 			    "item at index %d didn't match: %d != %d\n",
 			    i, testvector[i].value, sresvector[i].value);
+			ATF_CHECK_MSG(memcmp(testvector[i].spacetaker,
+			    sresvector[i].spacetaker, size) == 0,
+			    "Spacetaker corrupted at index %d\n", i);
+		}
 	}
 }
 
Index: lib/libc/tests/stdlib/test-sort.h
===================================================================
--- lib/libc/tests/stdlib/test-sort.h
+++ lib/libc/tests/stdlib/test-sort.h
@@ -33,6 +33,9 @@
 
 #include <atf-c.h>
 
+// Number of ints in the bigstruct array
+#define SPACE_LEN 100
+
 /*
  * Integer comparison function for stdlib sorting algorithms
  */
@@ -111,7 +114,7 @@
  */
 struct big {
 	int value;
-	int spacetaker[100];
+	int spacetaker[SPACE_LEN];
 };
 
 /*