diff --git a/base-test/org.eclipse.jdt.groovy.core.tests.compiler/src/org/eclipse/jdt/groovy/core/tests/xform/TypeCheckedTests.java b/base-test/org.eclipse.jdt.groovy.core.tests.compiler/src/org/eclipse/jdt/groovy/core/tests/xform/TypeCheckedTests.java
index 36b0a37e9a..7d469770ad 100644
--- a/base-test/org.eclipse.jdt.groovy.core.tests.compiler/src/org/eclipse/jdt/groovy/core/tests/xform/TypeCheckedTests.java
+++ b/base-test/org.eclipse.jdt.groovy.core.tests.compiler/src/org/eclipse/jdt/groovy/core/tests/xform/TypeCheckedTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2019 the original author or authors.
+ * Copyright 2009-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -112,4 +112,22 @@ public void testTypeChecked4() {
 
         runNegativeTest(sources, "");
     }
+
+    @Test
+    public void testTypeChecked5() {
+        //@formatter:off
+        String[] sources = {
+            "Foo.groovy",
+            "@groovy.transform.TypeChecked\n" +
+            "class Foo {\n" +
+            "  private Closure<String> normalizer\n" +
+            "  String normalize(String s) {\n" +
+            "    normalizer(s)" +
+            "  }\n" +
+            "}\n",
+        };
+        //@formatter:on
+
+        runNegativeTest(sources, "");
+    }
 }
diff --git a/base/org.codehaus.groovy24/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java b/base/org.codehaus.groovy24/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
index e499693982..efee2fef4f 100644
--- a/base/org.codehaus.groovy24/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
+++ b/base/org.codehaus.groovy24/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
@@ -3189,7 +3189,10 @@ public void visitMethodCallExpression(MethodCallExpression call) {
             boolean callArgsVisited = false;
             if (isCallOnClosure) {
                 // this is a closure.call() call
-                if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+                // GRECLIPSE edit
+                //if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+                if (objectExpression instanceof VariableExpression && ((VariableExpression) objectExpression).isThisExpression()) {
+                // GRECLIPSE end
                     // isClosureCall() check verified earlier that a field exists
                     FieldNode field = typeCheckingContext.getEnclosingClassNode().getDeclaredField(name);
                     GenericsType[] genericsTypes = field.getType().getGenericsTypes();
@@ -3571,7 +3574,10 @@ protected void storeTargetMethod(final Expression call, final MethodNode directM
 
     protected boolean isClosureCall(final String name, final Expression objectExpression, final Expression arguments) {
         if (objectExpression instanceof ClosureExpression && ("call".equals(name)||"doCall".equals(name))) return true;
-        if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+        // GRECLIPSE edit
+        //if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+        if (objectExpression instanceof VariableExpression && ((VariableExpression) objectExpression).isThisExpression()) {
+        // GRECLIPSE end
             FieldNode fieldNode = typeCheckingContext.getEnclosingClassNode().getDeclaredField(name);
             if (fieldNode != null) {
                 ClassNode type = fieldNode.getType();
diff --git a/base/org.codehaus.groovy25/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java b/base/org.codehaus.groovy25/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
index e57636dcb0..90d04668a5 100644
--- a/base/org.codehaus.groovy25/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
+++ b/base/org.codehaus.groovy25/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
@@ -3322,7 +3322,10 @@ public void visitMethodCallExpression(MethodCallExpression call) {
             boolean callArgsVisited = false;
             if (isCallOnClosure) {
                 // this is a closure.call() call
-                if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+                // GRECLIPSE edit
+                //if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+                if (objectExpression instanceof VariableExpression && ((VariableExpression) objectExpression).isThisExpression()) {
+                // GRECLIPSE end
                     // isClosureCall() check verified earlier that a field exists
                     FieldNode field = typeCheckingContext.getEnclosingClassNode().getDeclaredField(name);
                     GenericsType[] genericsTypes = field.getType().getGenericsTypes();
@@ -3719,7 +3722,10 @@ protected void storeTargetMethod(final Expression call, final MethodNode directM
     protected boolean isClosureCall(final String name, final Expression objectExpression, final Expression arguments) {
         if (objectExpression instanceof ClosureExpression && ("call".equals(name) || "doCall".equals(name)))
             return true;
-        if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+        // GRECLIPSE edit
+        //if (objectExpression == VariableExpression.THIS_EXPRESSION) {
+        if (objectExpression instanceof VariableExpression && ((VariableExpression) objectExpression).isThisExpression()) {
+        // GRECLIPSE end
             FieldNode fieldNode = typeCheckingContext.getEnclosingClassNode().getDeclaredField(name);
             if (fieldNode != null) {
                 ClassNode type = fieldNode.getType();