Index: test/asan/TestCases/strtol_strict.c
===================================================================
--- test/asan/TestCases/strtol_strict.c
+++ test/asan/TestCases/strtol_strict.c
@@ -41,7 +41,12 @@
   assert(r == 37);
 }
 
+void __attribute__((no_sanitize_address)) underflow_write(char *array) {
+  array[-1] = '\0';
+}
+
 void test3(char *array, char *endptr) {
+  underflow_write(array);
   // Buffer overflow if base is invalid.
   long r = strtol(array - 1, NULL, -1);
   assert(r == 0);
@@ -93,7 +98,7 @@
   // CHECK2: READ of size 4
   if (!strcmp(argv[1], "test3")) test3(array, endptr);
   // CHECK3: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
-  // CHECK3: READ of size 5
+  // CHECK3: READ of size 1
   if (!strcmp(argv[1], "test4")) test4(array, endptr);
   // CHECK4: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
   // CHECK4: READ of size 1
Index: test/asan/TestCases/strtoll_strict.c
===================================================================
--- test/asan/TestCases/strtoll_strict.c
+++ test/asan/TestCases/strtoll_strict.c
@@ -41,7 +41,12 @@
   assert(r == 37);
 }
 
+void __attribute__((no_sanitize_address)) underflow_write(char *array) {
+  array[-1] = '\0';
+}
+
 void test3(char *array, char *endptr) {
+  underflow_write(array);
   // Buffer overflow if base is invalid.
   long long r = strtoll(array - 1, NULL, -1);
   assert(r == 0);
@@ -93,7 +98,7 @@
   // CHECK2: READ of size 4
   if (!strcmp(argv[1], "test3")) test3(array, endptr);
   // CHECK3: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
-  // CHECK3: READ of size 5
+  // CHECK3: READ of size 1
   if (!strcmp(argv[1], "test4")) test4(array, endptr);
   // CHECK4: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
   // CHECK4: READ of size 1