diff --git a/changes/bug3175 b/changes/bug3175
new file mode 100644
index 0000000000..3360fbce00
--- /dev/null
+++ b/changes/bug3175
@@ -0,0 +1,7 @@
+  o Minor bugfixes:
+    - Resolve an untriggerable issue in smartlist_string_num_isin(),
+      where if the function had ever in the future been used to check
+      for the presence of a too-large number, it would have given an
+      incorrect result.  (Fortunately, we only used it for 16-bit
+      values.)  Fixes bug 3175; bugfix on Tor 0.1.0.1-rc.
+
diff --git a/src/common/container.c b/src/common/container.c
index af80f881f5..8635409d81 100644
--- a/src/common/container.c
+++ b/src/common/container.c
@@ -210,7 +210,7 @@ smartlist_string_isin_case(const smartlist_t *sl, const char *element)
 int
 smartlist_string_num_isin(const smartlist_t *sl, int num)
 {
-  char buf[16];
+  char buf[32]; /* long enough for 64-bit int, and then some. */
   tor_snprintf(buf,sizeof(buf),"%d", num);
   return smartlist_string_isin(sl, buf);
 }