diff --git a/build_info.json b/build_info.json
index 90b9eef..a6a2ab5 100644
--- a/build_info.json
+++ b/build_info.json
@@ -1,8 +1,8 @@
 {
     "build_time": "",
     "source files": {
-        "version": "v2.4.0-beta-3",
-        "commit": "f2a9f5f7036218d2e5184f704ecfa8a318f551c5",
+        "version": "v2.4.0-beta-4",
+        "commit": "a643415558f11073368644b7906b0130077ab003",
         "dirty": false
     },
     "pytex": {
@@ -144,9 +144,9 @@
         {
             "name": "mkessler-mathop.sty",
             "source file": "mathop.pysty",
-            "build time": "2021/12/12 19:15",
-            "source version": "v2.4.0-beta-3",
-            "source commit hash": "f2a9f5f7036218d2e5184f704ecfa8a318f551c5",
+            "build time": "2021/12/12 20:08",
+            "source version": "v2.4.0-beta-4",
+            "source commit hash": "a643415558f11073368644b7906b0130077ab003",
             "pytex version": "v1.0.0-18",
             "pytex commit hash": "126d420b7a6ed2d4b2a42d534ab2e12344869643",
             "dirty": false
diff --git a/math/mkessler-mathop.sty b/math/mkessler-mathop.sty
index 0f755a2..6ae4eea 100644
--- a/math/mkessler-mathop.sty
+++ b/math/mkessler-mathop.sty
@@ -27,7 +27,7 @@
 % 
 % Build details:
 %   PyTeX version: v1.0.0-18 (commit 126d420)
-%   Source code version: v2.4.0-beta-3 (commit f2a9f5f)
+%   Source code version: v2.4.0-beta-4 (commit a643415)
 % 
 % This LaTeX package is free software and distributed under the MIT License. You
 % may use it freely for your purposes. The latest version of the package can be
@@ -125,6 +125,7 @@
 \DeclareSimpleMathOperator{sgn}
 \DeclareSimpleMathOperator{coker}
 \DeclareSimpleMathOperator{rank}
+\DeclareSimpleMathOperator{rk}
 \DeclareSimpleMathOperator{Mat}
 \DeclareSimpleMathOperator{ev}
 \DeclareSimpleMathOperator{tr}