diff --git a/src/org/jetbrains/java/decompiler/code/CodeConstants.java b/src/org/jetbrains/java/decompiler/code/CodeConstants.java
index a8f9f36..720d2a7 100644
--- a/src/org/jetbrains/java/decompiler/code/CodeConstants.java
+++ b/src/org/jetbrains/java/decompiler/code/CodeConstants.java
@@ -1,6 +1,4 @@
-/*
- * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler.code;
 
 @SuppressWarnings({"unused", "SpellCheckingInspection"})
@@ -9,12 +7,16 @@ public interface CodeConstants {
   // BYTECODE VERSIONS
   // ----------------------------------------------------------------------
 
-  int BYTECODE_JAVA_LE_4 = 1;
-  int BYTECODE_JAVA_5 = 2;
-  int BYTECODE_JAVA_6 = 3;
-  int BYTECODE_JAVA_7 = 4;
-  int BYTECODE_JAVA_8 = 5;
-  int BYTECODE_JAVA_9 = 6;
+  int BYTECODE_JAVA_LE_4 = 48;
+  int BYTECODE_JAVA_5 = 49;
+  int BYTECODE_JAVA_6 = 50;
+  int BYTECODE_JAVA_7 = 51;
+  int BYTECODE_JAVA_8 = 52;
+  int BYTECODE_JAVA_9 = 53;
+  int BYTECODE_JAVA_10 = 54;
+  int BYTECODE_JAVA_11 = 55;
+  int BYTECODE_JAVA_12 = 56;
+  int BYTECODE_JAVA_13 = 57;
 
   // ----------------------------------------------------------------------
   // VARIABLE TYPES
diff --git a/src/org/jetbrains/java/decompiler/struct/StructClass.java b/src/org/jetbrains/java/decompiler/struct/StructClass.java
index 5815c89..02bb74a 100644
--- a/src/org/jetbrains/java/decompiler/struct/StructClass.java
+++ b/src/org/jetbrains/java/decompiler/struct/StructClass.java
@@ -1,4 +1,4 @@
-// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler.struct;
 
 import org.jetbrains.java.decompiler.code.CodeConstants;
@@ -157,28 +157,16 @@ public class StructClass extends StructMember {
   }
 
   public boolean isVersionGE_1_5() {
-    return (majorVersion > 48 || (majorVersion == 48 && minorVersion > 0)); // FIXME: check second condition
+    return (majorVersion > CodeConstants.BYTECODE_JAVA_LE_4 ||
+            (majorVersion == CodeConstants.BYTECODE_JAVA_LE_4 && minorVersion > 0)); // FIXME: check second condition
   }
 
   public boolean isVersionGE_1_7() {
-    return (majorVersion >= 51);
+    return (majorVersion >= CodeConstants.BYTECODE_JAVA_7);
   }
 
   public int getBytecodeVersion() {
-    switch (majorVersion) {
-      case 53:
-        return CodeConstants.BYTECODE_JAVA_9;
-      case 52:
-        return CodeConstants.BYTECODE_JAVA_8;
-      case 51:
-        return CodeConstants.BYTECODE_JAVA_7;
-      case 50:
-        return CodeConstants.BYTECODE_JAVA_6;
-      case 49:
-        return CodeConstants.BYTECODE_JAVA_5;
-    }
-
-    return CodeConstants.BYTECODE_JAVA_LE_4;
+    return majorVersion < CodeConstants.BYTECODE_JAVA_LE_4 ? CodeConstants.BYTECODE_JAVA_LE_4 : majorVersion;
   }
 
   @Override
diff --git a/test/org/jetbrains/java/decompiler/SingleClassesTest.java b/test/org/jetbrains/java/decompiler/SingleClassesTest.java
index 927e10a..1d0dc62 100644
--- a/test/org/jetbrains/java/decompiler/SingleClassesTest.java
+++ b/test/org/jetbrains/java/decompiler/SingleClassesTest.java
@@ -1,4 +1,4 @@
-// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.java.decompiler;
 
 import org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler;
@@ -74,6 +74,7 @@ public class SingleClassesTest {
            "pkg/TestShadowingSuperClass"); }
   @Test public void testStringConcat() { doTest("pkg/TestStringConcat"); }
   @Test public void testJava9StringConcat() { doTest("java9/TestJava9StringConcat"); }
+  @Test public void testJava11StringConcat() { doTest("java11/TestJava11StringConcat"); }
   @Test public void testMethodReferenceSameName() { doTest("pkg/TestMethodReferenceSameName"); }
   @Test public void testMethodReferenceLetterClass() { doTest("pkg/TestMethodReferenceLetterClass"); }
   @Test public void testConstructorReference() { doTest("pkg/TestConstructorReference"); }
diff --git a/testData/classes/java11/TestJava11StringConcat.class b/testData/classes/java11/TestJava11StringConcat.class
new file mode 100644
index 0000000..8ec1fbd
Binary files /dev/null and b/testData/classes/java11/TestJava11StringConcat.class differ
diff --git a/testData/results/TestJava11StringConcat.dec b/testData/results/TestJava11StringConcat.dec
new file mode 100644
index 0000000..68ab9c2
--- /dev/null
+++ b/testData/results/TestJava11StringConcat.dec
@@ -0,0 +1,27 @@
+package java11;
+
+public class TestJava11StringConcat {
+   public String test1(String var1, int var2) {
+      return var1 + var2;// 20
+   }
+
+   public String test2(String var1, int var2, Object var3) {
+      return "(" + var1 + "-" + var2 + "---" + var3 + ")";// 24
+   }
+}
+
+class 'java11/TestJava11StringConcat' {
+   method 'test1 (Ljava/lang/String;I)Ljava/lang/String;' {
+      2      4
+      7      4
+   }
+
+   method 'test2 (Ljava/lang/String;ILjava/lang/Object;)Ljava/lang/String;' {
+      3      8
+      8      8
+   }
+}
+
+Lines mapping:
+20 <-> 5
+24 <-> 9
diff --git a/testData/src/java11/TestJava11StringConcat.java b/testData/src/java11/TestJava11StringConcat.java
new file mode 100644
index 0000000..3f9e040
--- /dev/null
+++ b/testData/src/java11/TestJava11StringConcat.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package java11;
+
+public class TestJava11StringConcat {
+  public String test1(String prefix, int a) {
+    return prefix + a;
+  }
+
+  public String test2(String var, int b, Object c) {
+    return "(" + var + "-" + b + "---" + c + ")";
+  }
+}
\ No newline at end of file