diff --git a/blocks/procedures.js b/blocks/procedures.js
index 8e652ed39..21afdb7fa 100644
--- a/blocks/procedures.js
+++ b/blocks/procedures.js
@@ -721,10 +721,10 @@ const PROCEDURE_CALL_COMMON = {
     if (!mutatorOpen) {
       this.quarkConnections_ = {};
       this.quarkIds_ = null;
-    }
-    if (!paramIds) {
-      // Reset the quarks (a mutator is about to open).
-      return;
+    } else {
+      // fix #6091 - this call could cause an error when outside if-else
+      // expanding block while mutating prevents another error (ancient fix)
+      this.setCollapsed(false);
     }
     // Test arguments (arrays of strings) for changes. '\n' is not a valid
     // argument name character, so it is a valid delimiter here.
@@ -736,7 +736,6 @@ const PROCEDURE_CALL_COMMON = {
     if (paramIds.length !== paramNames.length) {
       throw RangeError('paramNames and paramIds must be the same length.');
     }
-    this.setCollapsed(false);
     if (!this.quarkIds_) {
       // Initialize tracking for this block.
       this.quarkConnections_ = {};
diff --git a/tests/mocha/serializer_test.js b/tests/mocha/serializer_test.js
index 85247cc98..9ddb4a90e 100644
--- a/tests/mocha/serializer_test.js
+++ b/tests/mocha/serializer_test.js
@@ -1674,12 +1674,52 @@ Serializer.Mutations.Procedure.Caller = new SerializerTestCase(
     '</mutation>' +
     '</block>' +
     '</xml>');
+Serializer.Mutations.Procedure.CollapsedProceduresCallreturn = new SerializerTestCase(
+    'CollapsedProceduresCallreturn',
+    '<xml xmlns="https://developers.google.com/blockly/xml">' +
+    '<variables>' +
+    '<variable id="aaaaaaaaaaaaaaaaaaaa">x</variable>' +
+    '</variables>' +
+    '<block type="procedures_defreturn" id="id******************" x="42" y="42">' +
+    '<mutation>' +
+    '<arg name="x" varid="aaaaaaaaaaaaaaaaaaaa"></arg>' +
+    '</mutation>' +
+    '<field name="NAME">do something</field>' +
+    '<comment pinned="false" h="80" w="160">Describe this function...</comment>' +
+    '</block>' +
+    '<block type="procedures_callreturn" id="id1*****************" collapsed="true" x="52" y="52">' +
+    '<mutation name="do something">' +
+    '<arg name="x"></arg>' +
+    '</mutation>' +
+    '</block>' +
+    '</xml>');
+Serializer.Mutations.Procedure.CollapsedProceduresCallnoreturn = new SerializerTestCase(
+    'CollapsedProceduresCallnoreturn',
+    '<xml xmlns="https://developers.google.com/blockly/xml">' +
+    '<variables>' +
+    '<variable id="aaaaaaaaaaaaaaaaaaaa">x</variable>' +
+    '</variables>' +
+    '<block type="procedures_defnoreturn" id="id******************" x="42" y="42">' +
+    '<mutation>' +
+    '<arg name="x" varid="aaaaaaaaaaaaaaaaaaaa"></arg>' +
+    '</mutation>' +
+    '<field name="NAME">do something</field>' +
+    '<comment pinned="false" h="80" w="160">Describe this function...</comment>' +
+    '</block>' +
+    '<block type="procedures_callnoreturn" id="id1*****************" collapsed="true" x="52" y="52">' +
+    '<mutation name="do something">' +
+    '<arg name="x"></arg>' +
+    '</mutation>' +
+    '</block>' +
+    '</xml>');
 Serializer.Mutations.Procedure.testCases = [
   Serializer.Mutations.Procedure.NoMutation,
   Serializer.Mutations.Procedure.Variables,
   Serializer.Mutations.Procedure.NoStatements,
   Serializer.Mutations.Procedure.IfReturn,
   Serializer.Mutations.Procedure.Caller,
+  Serializer.Mutations.Procedure.CollapsedProceduresCallreturn,
+  Serializer.Mutations.Procedure.CollapsedProceduresCallnoreturn,
 ];
 
 Serializer.Mutations.Procedure.Names = new SerializerTestSuite('Names');