diff --git a/resources/bytecode/javFiles/Bug310.jav b/resources/bytecode/javFiles/Bug310.jav
new file mode 100644
index 00000000..05393385
--- /dev/null
+++ b/resources/bytecode/javFiles/Bug310.jav
@@ -0,0 +1,9 @@
+import java.lang.Integer;
+import java.lang.String;
+
+public class Bug310 {
+    Integer i = 3;
+    public toString() {
+        return i.toString();
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java b/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
index dda6aadd..601316f6 100644
--- a/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
+++ b/src/main/java/de/dhbwstuttgart/bytecode/Codegen.java
@@ -1029,8 +1029,10 @@ public class Codegen {
             break;
         }
         case TargetMethodCall call: {
-            if (!call.isStatic())
+            if (!call.isStatic()) {
                 generate(state, call.expr());
+                boxPrimitive(state, call.expr().type());
+            }
             for (var i = 0; i < call.args().size(); i++) {
                 var e = call.args().get(i);
                 var arg = call.parameterTypes().get(i);
diff --git a/src/test/java/TestComplete.java b/src/test/java/TestComplete.java
index f3455c9b..f06f1a19 100644
--- a/src/test/java/TestComplete.java
+++ b/src/test/java/TestComplete.java
@@ -1031,4 +1031,12 @@ public class TestComplete {
         var instance = clazz.getDeclaredConstructor().newInstance();
         clazz.getDeclaredMethod("main").invoke(instance);
     }
+
+    @Test
+    public void testBug310() throws Exception {
+        var classFiles = generateClassFiles(new ByteArrayClassLoader(), "Bug310.jav");
+        var clazz = classFiles.get("Bug310");
+        var instance = clazz.getDeclaredConstructor().newInstance();
+        assertEquals(clazz.getDeclaredMethod("toString").invoke(instance), "3");
+    }
 }