diff --git a/core/connection_checker.js b/core/connection_checker.js
index 15e044152..d05de79e4 100644
--- a/core/connection_checker.js
+++ b/core/connection_checker.js
@@ -32,12 +32,14 @@ Blockly.ConnectionChecker = function() {
  * @param {Blockly.Connection} b Connection to check compatibility with.
  * @param {boolean} isDragging True if the connection is being made by dragging
  *     a block.
+ * @param {number=} opt_distance The max allowable distance between the
+ *     connections for drag checks.
  * @return {boolean} Whether the connection is legal.
  * @public
  */
 Blockly.ConnectionChecker.prototype.canConnect = function(a, b,
-    isDragging) {
-  return this.canConnectWithReason(a, b, isDragging) ==
+    isDragging, opt_distance) {
+  return this.canConnectWithReason(a, b, isDragging, opt_distance) ==
       Blockly.Connection.CAN_CONNECT;
 };
 
@@ -48,12 +50,14 @@ Blockly.ConnectionChecker.prototype.canConnect = function(a, b,
  * @param {Blockly.Connection} b Connection to check compatibility with.
  * @param {boolean} isDragging True if the connection is being made by dragging
  *     a block.
+ * @param {number=} opt_distance The max allowable distance between the
+ *     connections for drag checks.
  * @return {number} Blockly.Connection.CAN_CONNECT if the connection is legal,
  *    an error code otherwise.
  * @public
  */
 Blockly.ConnectionChecker.prototype.canConnectWithReason = function(
-    a, b, isDragging) {
+    a, b, isDragging, opt_distance) {
   var safety = this.doSafetyChecks(a, b);
   if (safety != Blockly.Connection.CAN_CONNECT) {
     return safety;
@@ -66,7 +70,11 @@ Blockly.ConnectionChecker.prototype.canConnectWithReason = function(
     return Blockly.Connection.REASON_CHECKS_FAILED;
   }
 
-  if (isDragging && this.doDragChecks(connOne, connTwo)) {
+  if (isDragging &&
+      !this.doDragChecks(
+          /** @type {!Blockly.RenderedConnection} **/ (a),
+          /** @type {!Blockly.RenderedConnection} **/ (b),
+          opt_distance || 0)) {
     return Blockly.Connection.REASON_DRAG_CHECKS_FAILED;
   }
 
@@ -169,12 +177,17 @@ Blockly.ConnectionChecker.prototype.doTypeChecks = function(a, b) {
 
 /**
  * Check whether this connection can be made by dragging.
- * @param {!Blockly.Connection} a Connection to compare.
- * @param {!Blockly.Connection} b Connection to compare against.
- * @return {boolean} True if the connections share a type.
+ * @param {!Blockly.RenderedConnection} a Connection to compare.
+ * @param {!Blockly.RenderedConnection} b Connection to compare against.
+ * @param {number} distance The maximum allowable distance between connections.
+ * @return {boolean} True if the connection is allowed during a drag.
  * @public
  */
-Blockly.ConnectionChecker.prototype.doDragChecks = function(a, b) {
+Blockly.ConnectionChecker.prototype.doDragChecks = function(a, b, distance) {
+  if (a.distanceFrom(b) > distance) {
+    return false;
+  }
+
   // Don't consider insertion markers.
   if (b.getSourceBlock().isInsertionMarker()) {
     return false;
diff --git a/core/connection_db.js b/core/connection_db.js
index 2026678d2..d347ddbe0 100644
--- a/core/connection_db.js
+++ b/core/connection_db.js
@@ -247,17 +247,14 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
   var bestConnection = null;
   var bestRadius = maxRadius;
   var temp;
-  var curDistance;
 
   // Walk forward and back on the y axis looking for the closest x,y point.
   var pointerMin = closestIndex - 1;
   while (pointerMin >= 0 && this.isInYRange_(pointerMin, conn.y, maxRadius)) {
     temp = this.connections_[pointerMin];
-    curDistance = temp.distanceFrom(conn);
-    if (curDistance <= bestRadius &&
-        this.connectionChecker_.canConnect(conn, temp, true)) {
+    if (this.connectionChecker_.canConnect(conn, temp, true, bestRadius)) {
       bestConnection = temp;
-      bestRadius = curDistance;
+      bestRadius = temp.distanceFrom(conn);
     }
     pointerMin--;
   }
@@ -266,11 +263,9 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
   while (pointerMax < this.connections_.length &&
       this.isInYRange_(pointerMax, conn.y, maxRadius)) {
     temp = this.connections_[pointerMax];
-    curDistance = temp.distanceFrom(conn);
-    if (curDistance <= bestRadius &&
-        this.connectionChecker_.canConnect(conn, temp, true)) {
+    if (this.connectionChecker_.canConnect(conn, temp, true, bestRadius)) {
       bestConnection = temp;
-      bestRadius = curDistance;
+      bestRadius = temp.distanceFrom(conn);
     }
     pointerMax++;
   }
diff --git a/core/interfaces/i_connection_checker.js b/core/interfaces/i_connection_checker.js
index 6d386743c..505401666 100644
--- a/core/interfaces/i_connection_checker.js
+++ b/core/interfaces/i_connection_checker.js
@@ -29,6 +29,8 @@ Blockly.IConnectionChecker = function() {};
  * @param {Blockly.Connection} b Connection to check compatibility with.
  * @param {boolean} isDragging True if the connection is being made by dragging
  *     a block.
+ * @param {number=} opt_distance The max allowable distance between the
+ *     connections for drag checks.
  * @return {boolean} Whether the connection is legal.
  * @public
  */
@@ -41,6 +43,8 @@ Blockly.IConnectionChecker.prototype.canConnect;
  * @param {Blockly.Connection} b Connection to check compatibility with.
  * @param {boolean} isDragging True if the connection is being made by dragging
  *     a block.
+ * @param {number=} opt_distance The max allowable distance between the
+ *     connections for drag checks.
  * @return {number} Blockly.Connection.CAN_CONNECT if the connection is legal,
  *    an error code otherwise.
  * @public
@@ -81,9 +85,10 @@ Blockly.IConnectionChecker.prototype.doTypeChecks;
 
 /**
  * Check whether this connection can be made by dragging.
- * @param {!Blockly.Connection} a Connection to compare.
- * @param {!Blockly.Connection} b Connection to compare against.
- * @return {boolean} True if the connections share a type.
+ * @param {!Blockly.RenderedConnection} a Connection to compare.
+ * @param {!Blockly.RenderedConnection} b Connection to compare against.
+ * @param {number} distance The maximum allowable distance between connections.
+ * @return {boolean} True if the connection is allowed during a drag.
  * @public
  */
 Blockly.IConnectionChecker.prototype.doDragChecks;
diff --git a/tests/mocha/connection_db_test.js b/tests/mocha/connection_db_test.js
index f8dccd5d0..2013be0f9 100644
--- a/tests/mocha/connection_db_test.js
+++ b/tests/mocha/connection_db_test.js
@@ -190,14 +190,26 @@ suite('Connection Database', function() {
       this.assertOrder();
     });
   });
-  // Does not cover logic for isConnectionAllowed
+
   suite('Search For Closest', function() {
     setup(function() {
-      this.allowedStub = null;
-      this.allowedStub = sinon.stub(this.database.connectionChecker_, 'canConnect')
-          .callsFake(function(_dragging, _candidate) {
+      this.allowedStubs = [];
+      // Ignore type checks.
+      this.allowedStubs.push(sinon.stub(this.database.connectionChecker_, 'doTypeChecks')
+          .callsFake(function(_a, _b) {
             return true;
-          });
+          }));
+      // Ignore safety checks.
+      this.allowedStubs.push(sinon.stub(this.database.connectionChecker_, 'doSafetyChecks')
+          .callsFake(function(_a, _b) {
+            return Blockly.Connection.CAN_CONNECT;
+          }));
+      // Skip everything but the distance checks.
+      this.allowedStubs.push(sinon.stub(this.database.connectionChecker_, 'doDragChecks')
+          .callsFake(function(a, b, distance) {
+            return a.distanceFrom(b) <= distance;
+          }));
+
       this.createCheckConnection = function(x, y) {
         var checkConnection = this.createConnection(x, y, Blockly.NEXT_STATEMENT,
             new Blockly.ConnectionDB());
@@ -205,9 +217,7 @@ suite('Connection Database', function() {
       };
     });
     teardown(function() {
-      if (this.allowedStub) {
-        this.allowedStub.restore();
-      }
+      this.allowedStubs.forEach(stub => stub.restore());
     });
     test('Empty Database', function() {
       var checkConnection = this.createConnection(0, 0, Blockly.NEXT_STATEMENT,