diff --git a/HISTORY.md b/HISTORY.md
index a02790a2..830683c6 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -6,6 +6,7 @@
     * raycasting: new "ray length" option in the "relation TO object" primitive
     * hyperdyadic MIN and MAX primitives reachable via "relabel"
     * hyperdyadic less / great than or equals primitives reachable via "relabel"
+    * hyperdyadic ATAN2 primitive reachable via "relabel"
     * new SIGN function in arithmetic dropdown
 * **Notable Changes:**
     * searching for blocks and keyboard entry now includes the contents of dropdown menus
@@ -23,6 +24,7 @@
 
 ### 2020-12-09
 * Tamil translation update, thanks, Barthdry!
+* threads, objects: added hyperdyadic ATAN2 primitive reachable via "relabel"
 
 ### 2020-12-07
 * GUI: improved SVG loading, thanks, Joan!
diff --git a/snap.html b/snap.html
index adf915c6..8da4dddf 100755
--- a/snap.html
+++ b/snap.html
@@ -9,8 +9,8 @@
         <script src="src/symbols.js?version=2020-10-07"></script>
         <script src="src/widgets.js?version=2020-10-06"></script>
         <script src="src/blocks.js?version=2020-12-07"></script>
-        <script src="src/threads.js?version=2020-12-07"></script>
-        <script src="src/objects.js?version=2020-12-07"></script>
+        <script src="src/threads.js?version=2020-12-09"></script>
+        <script src="src/objects.js?version=2020-12-09"></script>
         <script src="src/gui.js?version=2020-12-07"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
         <script src="src/lists.js?version=2020-12-01"></script>
diff --git a/src/objects.js b/src/objects.js
index 6f918fd4..6460b89d 100644
--- a/src/objects.js
+++ b/src/objects.js
@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph,  BooleanSlotMorph,
 localize, TableMorph, TableFrameMorph, normalizeCanvas, VectorPaintEditorMorph,
 AlignmentMorph, Process, WorldMap, copyCanvas, useBlurredShadows*/
 
-modules.objects = '2020-December-07';
+modules.objects = '2020-December-09';
 
 var SpriteMorph;
 var StageMorph;
@@ -1106,6 +1106,11 @@ SpriteMorph.prototype.initBlocks = function () {
             category: 'operators',
             spec: '%n mod %n'
         },
+        reportAtan2: {
+            type: 'reporter',
+            category: 'operators',
+            spec: 'atan2 %n ÷ %n'
+        },
         reportMin: {
             type: 'reporter',
             category: 'operators',
@@ -1649,21 +1654,28 @@ SpriteMorph.prototype.blockAlternatives = {
 
     // operators:
     reportSum: ['reportDifference', 'reportProduct', 'reportQuotient',
-        'reportPower', 'reportModulus', 'reportMin', 'reportMax'],
+        'reportPower', 'reportModulus', 'reportAtan2', 'reportMin',
+        'reportMax'],
     reportDifference: ['reportSum', 'reportProduct', 'reportQuotient',
-        'reportPower', 'reportModulus', 'reportMin', 'reportMax'],
+        'reportPower', 'reportModulus', 'reportAtan2', 'reportMin',
+        'reportMax'],
     reportProduct: ['reportDifference', 'reportSum', 'reportQuotient',
-        'reportPower', 'reportModulus', 'reportMin', 'reportMax'],
+        'reportPower', 'reportModulus', 'reportAtan2', 'reportMin',
+        'reportMax'],
     reportQuotient: ['reportDifference', 'reportProduct', 'reportSum',
-        'reportPower', 'reportModulus', 'reportMin', 'reportMax'],
+        'reportPower', 'reportModulus', 'reportAtan2', 'reportMin',
+        'reportMax'],
     reportPower: ['reportDifference', 'reportProduct', 'reportSum',
-        'reportQuotient', 'reportModulus', 'reportMin', 'reportMax'],
-    reportModulus: ['reportDifference', 'reportProduct', 'reportSum',
-        'reportQuotient', 'reportPower', 'reportMin', 'reportMax'],
-    reportMin: ['reportSum', 'reportDifference', 'reportProduct',
-        'reportQuotient', 'reportPower', 'reportModulus', 'reportMax'],
-    reportMax: ['reportSum', 'reportDifference', 'reportProduct',
-        'reportQuotient', 'reportPower', 'reportModulus', 'reportMin'],
+        'reportQuotient', 'reportModulus', 'reportAtan2', 'reportMin',
+        'reportMax'],
+    reportModulus: ['reportAtan2', 'reportDifference', 'reportProduct',
+        'reportSum','reportQuotient', 'reportPower', 'reportMin', 'reportMax'],
+    reportAtan2: ['reportModulus', 'reportDifference', 'reportProduct',
+        'reportSum','reportQuotient', 'reportPower', 'reportMin', 'reportMax'],
+    reportMin: ['reportMax', 'reportSum', 'reportDifference', 'reportProduct',
+        'reportQuotient', 'reportPower', 'reportModulus', 'reportAtan2'],
+    reportMax: ['reportMin', 'reportSum', 'reportDifference', 'reportProduct',
+        'reportQuotient', 'reportPower', 'reportModulus', 'reportAtan2'],
     reportLessThan: ['reportLessThanOrEquals', 'reportEquals',
         'reportGreaterThan', 'reportGreaterThanOrEquals'],
     reportEquals: ['reportLessThan', 'reportLessThanOrEquals',
diff --git a/src/threads.js b/src/threads.js
index 122b57cd..2ee24774 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -61,7 +61,7 @@ StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy, Map,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, BLACK,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume*/
 
-modules.threads = '2020-December-07';
+modules.threads = '2020-December-09';
 
 var ThreadManager;
 var Process;
@@ -3721,6 +3721,14 @@ Process.prototype.reportBasicModulus = function (a, b) {
     return ((x % y) + y) % y;
 };
 
+Process.prototype.reportAtan2 = function (a, b) {
+    return this.hyperDyadic(this.reportBasicAtan2, a, b);
+};
+
+Process.prototype.reportBasicAtan2 = function (a, b) {
+    return degrees(Math.atan2(+a, +b));
+};
+
 Process.prototype.reportMin = function (a, b) {
     return this.hyperDyadic(this.reportBasicMin, a, b);
 };