diff --git a/include/ConflictSet.h b/include/ConflictSet.h
index c1eabba..f493778 100644
--- a/include/ConflictSet.h
+++ b/include/ConflictSet.h
@@ -52,7 +52,7 @@ struct __attribute__((__visibility__("default"))) ConflictSet {
   struct ReadRange {
     Key begin;
     /** `end` having length 0 denotes that this range is the single key {begin}.
-     * Otherwise this denotes the range [begin, end) */
+     * Otherwise this denotes the range [begin, end), and begin must be < end */
     Key end;
     /** `readVersion` older than the the oldestVersion or the version of the
      * latest call to `addWrites` minus two billion will result in `TooOld` */
@@ -63,7 +63,7 @@ struct __attribute__((__visibility__("default"))) ConflictSet {
   struct WriteRange {
     Key begin;
     /** `end` having length 0 denotes that this range is the single key {begin}.
-     * Otherwise this denotes the range [begin, end) */
+     * Otherwise this denotes the range [begin, end), and begin must be < end */
     Key end;
   };
 
@@ -139,7 +139,7 @@ typedef struct {
 typedef struct {
   ConflictSet_Key begin;
   /** `end` having length 0 denotes that this range is the single key {begin}.
-   * Otherwise this denotes the range [begin, end) */
+   * Otherwise this denotes the range [begin, end), and begin must be < end */
   ConflictSet_Key end;
   /** `readVersion` older than the the oldestVersion or the version of the
    * latest call to `addWrites` minus two billion will result in `TooOld` */
@@ -150,7 +150,7 @@ typedef struct {
 typedef struct {
   ConflictSet_Key begin;
   /** `end` having length 0 denotes that this range is the single key {begin}.
-   * Otherwise this denotes the range [begin, end) */
+   * Otherwise this denotes the range [begin, end), and begin must be < end */
   ConflictSet_Key end;
 } ConflictSet_WriteRange;