diff --git a/lib/checkclass.cpp b/lib/checkclass.cpp
index 76d87feba..7f90adee1 100644
--- a/lib/checkclass.cpp
+++ b/lib/checkclass.cpp
@@ -2221,6 +2221,13 @@ bool CheckClass::checkConstFunc(const SpaceInfo *info, const Token *tok)
                 isconst = false;
                 break;
             }
+
+            // FIXME: I assume that a member union/struct variable is assigned.
+            else if (Token::Match(tok1->tokAt(-2), ". %var%"))
+            {
+                isconst = false;
+                break;
+            }
         }
 
         // streaming: <<
diff --git a/test/testclass.cpp b/test/testclass.cpp
index 1e7e5d37f..31e222551 100644
--- a/test/testclass.cpp
+++ b/test/testclass.cpp
@@ -157,6 +157,7 @@ private:
         TEST_CASE(constVirtualFunc);
         TEST_CASE(constIfCfg);  // ticket #1881 - fp when there are #if
         TEST_CASE(constFriend); // ticket #1921 - fp for friend function
+        TEST_CASE(constUnion);	// ticket #2111 - fp when there are union
 
         TEST_CASE(symboldatabase1);
         TEST_CASE(symboldatabase2);
@@ -4409,6 +4410,21 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void constUnion() // ticket #2111
+    {
+        checkConst("class foo {\n"
+                   "public:\n"
+                   "    union {\n"
+                   "        int i;\n"
+                   "        float f;\n"
+                   "    } d;\n"
+                   "    void setf(float x) {\n"
+                   "        d.f = x;\n"
+                   "    }\n"
+                   "}");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void symboldatabase1()
     {
         checkConst("namespace foo {\n"