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 9dbe547d0b..b575aab13b 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
@@ -4348,6 +4348,25 @@ public void testTypeChecked10323() {
             "----------\n");
     }
 
+    @Test
+    public void testTypeChecked10324() {
+        //@formatter:off
+        String[] sources = {
+            "Main.groovy",
+            "class C<T> {\n" +
+            "}\n" +
+            "def <X> X m(C<X> c) {\n" +
+            "}\n" +
+            "@groovy.transform.TypeChecked\n" +
+            "void test() {\n" +
+            "  Set<String> x = m(new C<>())\n" +
+            "}\n",
+        };
+        //@formatter:on
+
+        runNegativeTest(sources, "");
+    }
+
     @Test
     public void testTypeChecked10325() {
         //@formatter:off
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 24095ab43c..eb5bae73f5 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
@@ -982,13 +982,13 @@ && isAssignment(enclosingBinaryExpression.getOperation().getType())) {
                 if (rightExpression instanceof ConstructorCallExpression) {
                     inferDiamondType((ConstructorCallExpression) rightExpression, lType);
                 }
-                // GRECLIPSE add -- unchecked assignment
+                // GRECLIPSE add -- GROOVY-10051, GROOVY-10235, GROOVY-10324
                 if (lType.isUsingGenerics() && missesGenericsTypes(resultType)) {
                     // the inferred type of the binary expression is the type of the RHS
                     // "completed" with generics type information available from the LHS
                     if (lType.equals(resultType)) {
                         if (!lType.isGenericsPlaceHolder()) resultType = lType;
-                    } else {
+                    } else if (!resultType.isGenericsPlaceHolder()) {
                         Map<GenericsTypeName, GenericsType> gt = new HashMap<>();
                         extractGenericsConnections(gt, resultType, resultType.redirect());
                         extractGenericsConnections(gt, lType, getNextSuperClass(resultType, lType));
diff --git a/base/org.codehaus.groovy30/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java b/base/org.codehaus.groovy30/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
index 7df1d7e534..624e22dfc8 100644
--- a/base/org.codehaus.groovy30/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
+++ b/base/org.codehaus.groovy30/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
@@ -867,13 +867,13 @@ && isAssignment(enclosingBinaryExpression.getOperation().getType())) {
                 if (rightExpression instanceof ConstructorCallExpression) {
                     inferDiamondType((ConstructorCallExpression) rightExpression, lType);
                 }
-                // GRECLIPSE add -- unchecked assignment
+                // GRECLIPSE add -- GROOVY-10051, GROOVY-10235, GROOVY-10324
                 if (lType.isUsingGenerics() && missesGenericsTypes(resultType)) {
                     // the inferred type of the binary expression is the type of the RHS
                     // "completed" with generics type information available from the LHS
                     if (lType.equals(resultType)) {
                         if (!lType.isGenericsPlaceHolder()) resultType = lType;
-                    } else {
+                    } else if (!resultType.isGenericsPlaceHolder()) {
                         Map<GenericsTypeName, GenericsType> gt = new HashMap<>();
                         extractGenericsConnections(gt, resultType, resultType.redirect());
                         extractGenericsConnections(gt, lType, getNextSuperClass(resultType, lType));
diff --git a/base/org.codehaus.groovy40/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java b/base/org.codehaus.groovy40/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
index 151f6137e6..4c88778a54 100644
--- a/base/org.codehaus.groovy40/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
+++ b/base/org.codehaus.groovy40/src/org/codehaus/groovy/transform/stc/StaticTypeCheckingVisitor.java
@@ -866,13 +866,13 @@ && isAssignment(enclosingBinaryExpression.getOperation().getType())) {
 
                     // the inferred type of the binary expression is the type of the RHS
                     // "completed" with generics type information available from the LHS
-                    /* GRECLIPSE edit -- GROOVY-10235
+                    /* GRECLIPSE edit -- GROOVY-10051, GROOVY-10235, GROOVY-10324
                     if (!resultType.isGenericsPlaceHolder()) // plain reference drops placeholder
                         resultType = GenericsUtils.parameterizeType(lType, resultType.getPlainNodeReference());
                     */
                     if (lType.equals(resultType)) {
                         if (!lType.isGenericsPlaceHolder()) resultType = lType;
-                    } else {
+                    } else if (!resultType.isGenericsPlaceHolder()) {
                         Map<GenericsTypeName, GenericsType> gt = new HashMap<>();
                         extractGenericsConnections(gt, resultType, resultType.redirect());
                         extractGenericsConnections(gt, lType, getNextSuperClass(resultType, lType));