diff --git a/tests/mocha/astnode_test.js b/tests/mocha/astnode_test.js
index bfd4e5972..793bdcf9a 100644
--- a/tests/mocha/astnode_test.js
+++ b/tests/mocha/astnode_test.js
@@ -321,8 +321,8 @@ suite('ASTNode', function() {
       delete this.blocks.dummyInput;
       delete this.blocks.dummyInputValue;
       delete this.blocks.fieldWithOutput2;
-      
 
+      delete Blockly.Blocks['output_next'];
       delete Blockly.Blocks['fields_and_input2'];
       delete Blockly.Blocks['two_fields'];
       delete Blockly.Blocks['fields_and_input'];
diff --git a/tests/mocha/block_test.js b/tests/mocha/block_test.js
index 1e7823bea..58e20aa69 100644
--- a/tests/mocha/block_test.js
+++ b/tests/mocha/block_test.js
@@ -44,6 +44,7 @@ suite('Blocks', function() {
   });
   teardown(function() {
     this.workspace.dispose();
+    delete Blockly.Blocks['empty_block'];
     delete Blockly.Blocks['stack_block'];
     delete Blockly.Blocks['row_block'];
     delete Blockly.Blocks['statement_block'];
@@ -324,21 +325,10 @@ suite('Blocks', function() {
             }
           ]
         },
-        {
-          "type": "statement_block",
-          "message0": "%1",
-          "args0": [
-            {
-              "type": "input_statement",
-              "name": "STATEMENT"
-            }
-          ]
-        },
       ]);
     });
     teardown(function() {
       delete Blockly.Blocks['value_block'];
-      delete Blockly.Blocks['statement_block'];
     });
 
     suite('Value', function() {
@@ -1030,17 +1020,9 @@ suite('Blocks', function() {
   });
   suite('Comments', function() {
     setup(function() {
-      Blockly.defineBlocksWithJsonArray([
-        {
-          "type": "empty_block",
-          "message0": "",
-          "args0": []
-        },
-      ]);
       this.eventSpy = sinon.spy(Blockly.Events, 'fire');
     });
     teardown(function() {
-      delete Blockly.Blocks['empty_block'];
       this.eventSpy.restore();
     });
     suite('Set/Get Text', function() {
diff --git a/tests/mocha/navigation_test.js b/tests/mocha/navigation_test.js
index a176daeb5..168577412 100644
--- a/tests/mocha/navigation_test.js
+++ b/tests/mocha/navigation_test.js
@@ -367,6 +367,10 @@ suite('Navigation', function() {
         }
       };
     });
+    teardown(function() {
+      delete Blockly.Blocks['basic_block'];
+      this.workspace.dispose();
+    });
     test('Action does not exist', function() {
       var block = this.workspace.getTopBlocks()[0];
       var field = block.inputList[0].fieldRow[0];
@@ -432,7 +436,6 @@ suite('Navigation', function() {
       chai.assert.isTrue(Blockly.navigation.focusWorkspace_.calledOnce);
       chai.assert.isTrue(Blockly.getMainWorkspace().keyboardAccessibilityMode);
       Blockly.navigation.focusWorkspace_.restore();
-      this.workspace.dispose();
     });
 
     suite('Test key press in read only mode', function() {
@@ -630,6 +633,7 @@ suite('Navigation', function() {
     });
 
     teardown(function() {
+      delete Blockly.Blocks['inline_block'];
       delete Blockly.Blocks['basic_block'];
       this.workspace.dispose();
     });