diff --git a/base-test/org.eclipse.jdt.groovy.core.tests.builder/src/org/eclipse/jdt/core/groovy/tests/search/InferencingTests.java b/base-test/org.eclipse.jdt.groovy.core.tests.builder/src/org/eclipse/jdt/core/groovy/tests/search/InferencingTests.java
index 6fb11b3446..2f44af7090 100644
--- a/base-test/org.eclipse.jdt.groovy.core.tests.builder/src/org/eclipse/jdt/core/groovy/tests/search/InferencingTests.java
+++ b/base-test/org.eclipse.jdt.groovy.core.tests.builder/src/org/eclipse/jdt/core/groovy/tests/search/InferencingTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2017 the original author or authors.
+ * Copyright 2009-2018 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.
@@ -2281,4 +2281,61 @@ public void testLocalTypeAndDefaultImportCollision() {
         assertExprType(contents, "instance", "domain.Calendar");
         assertExprType(contents, "cal", "domain.Calendar");
     }
+
+    @Test // https://github.com/groovy/groovy-eclipse/issues/405
+    public void testMethodOverloadsAndImperfectArgumentMatching() {
+        createJavaUnit("MyEnum", "enum MyEnum { A, B }");
+
+        String contents = "class Issue405 {\n" +
+            "  void meth(String s, MyEnum e) {\n" +
+            "    def d1, d2\n" +
+            "    switch (e) {\n" +
+            "    case MyEnum.A:\n" +
+            "      d1 = new Date()\n" +
+            "      d2 = new Date()\n" +
+            "      break\n" +
+            "    case MyEnum.B:\n" +
+            "      d1 = null\n" +
+            "      d2 = null\n" +
+            "      break\n" +
+            "    }\n" +
+            "    meth(s, d1, d2)\n" +
+            "  }\n" +
+            "  void meth(String s, Date d1, Date d2) {\n" +
+            "  }\n" +
+            "}";
+        int offset = contents.indexOf("meth(s");
+        MethodNode m = assertDeclaration(contents, offset, offset + 4, "Issue405", "meth", DeclarationKind.METHOD);
+        assertEquals("Expected 'meth(String, Date, Date)' but was 'meth(String, MyEnum)'", 3, m.getParameters().length);
+    }
+
+    @Test
+    public void testMethodOverloadsAndPerfectArgumentMatching() {
+        createJavaUnit("MyEnum", "enum MyEnum { A, B }");
+
+        String contents = "class Issue405 {\n" +
+            "  void meth(String s, MyEnum e) {\n" +
+            "    def d1, d2\n" +
+            "    switch (e) {\n" +
+            "    case MyEnum.A:\n" +
+            "      d1 = new Date()\n" +
+            "      d2 = new Date()\n" +
+            "      break\n" +
+            "    case MyEnum.B:\n" +
+            "      d1 = null\n" +
+            "      d2 = null\n" +
+            "      break\n" +
+            "    }\n" +
+            "    meth(s, d1, d2)\n" +
+            "  }\n" +
+            "  void meth(String s, Date d1, Date d2) {\n" +
+            "  }\n" +
+            "  void meth(String s, Object o1, Object o2) {\n" +
+            "  }\n" +
+            "}";
+        int offset = contents.indexOf("meth(s");
+        MethodNode m = assertDeclaration(contents, offset, offset + 4, "Issue405", "meth", DeclarationKind.METHOD);
+        assertTrue("Expected 'meth(String, Object, Object)' but was 'meth(String, MyEnum)' or 'meth(String, Date, Date)'",
+            m.getParameters().length == 3 && m.getParameters()[2].getType().getNameWithoutPackage().equals("Object"));
+    }
 }
diff --git a/base/org.eclipse.jdt.groovy.core/src/org/eclipse/jdt/groovy/search/SimpleTypeLookup.java b/base/org.eclipse.jdt.groovy.core/src/org/eclipse/jdt/groovy/search/SimpleTypeLookup.java
index 0c019be6dd..084989b87d 100644
--- a/base/org.eclipse.jdt.groovy.core/src/org/eclipse/jdt/groovy/search/SimpleTypeLookup.java
+++ b/base/org.eclipse.jdt.groovy.core/src/org/eclipse/jdt/groovy/search/SimpleTypeLookup.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2017 the original author or authors.
+ * Copyright 2009-2018 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.
@@ -646,25 +646,22 @@ protected MethodNode findMethodDeclaration0(List<MethodNode> candidates, List<Cl
             arguments = Collections.emptyList();
         }
 
-        // prefer retrieving the method with the same number of args as specified in the parameter.
-        // if none exists, or parameter is -1, then arbitrarily choose the first.
-        for (Iterator<MethodNode> iterator = candidates.iterator(); iterator.hasNext();) {
-            MethodNode maybeMethod = iterator.next();
-            Parameter[] parameters = maybeMethod.getParameters();
+        // prefer retrieving the method with the same number of parameters as arguments
+        // if none exists, then arbitrarily choose the first; TODO: handle variadic methods
+        for (MethodNode candidate : candidates) {
+            Parameter[] parameters = candidate.getParameters();
             if (parameters.length == 0 && arguments.isEmpty()) {
-                return maybeMethod.getOriginal();
+                return candidate.getOriginal();
             }
             if (parameters.length == arguments.size()) {
                 Boolean suitable = isTypeCompatible(arguments, parameters);
                 if (Boolean.TRUE.equals(suitable)) {
-                    return maybeMethod.getOriginal();
+                    return candidate.getOriginal();
                 }
-                if (!Boolean.FALSE.equals(suitable)) {
-                    closestMatch = maybeMethod.getOriginal();
-                    continue; // don't remove
+                if (!Boolean.FALSE.equals(suitable) || closestMatch.getParameters().length != arguments.size()) {
+                    closestMatch = candidate.getOriginal();
                 }
             }
-            iterator.remove();
         }
         return closestMatch;
     }