diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 31154e5d4..83c30a245 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -407,6 +407,18 @@ static void setTokenValue(Token* tok, const ValueFlow::Value &value)
         }
     }
 
+    // !
+    else if (parent->str() == "!") {
+        std::list<ValueFlow::Value>::const_iterator it;
+        for (it = tok->values.begin(); it != tok->values.end(); ++it) {
+            if (it->tokvalue)
+                continue;
+            ValueFlow::Value v(*it);
+            v.intvalue = !v.intvalue;
+            setTokenValue(parent, v);
+        }
+    }
+
     // Array element
     else if (parent->str() == "[" && parent->astOperand1() && parent->astOperand2()) {
         std::list<ValueFlow::Value>::const_iterator value1, value2;
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index dd8a54c12..83ce94876 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -265,6 +265,15 @@ private:
         ASSERT_EQUALS(2, values.front().intvalue);
         ASSERT_EQUALS(3, values.back().intvalue);
 
+        // !
+        code  = "void f(int x) {\n"
+                "    a = !x;\n"
+                "    if (x==0) {}\n"
+                "}";
+        values = tokenValues(code,"!");
+        ASSERT_EQUALS(1U, values.size());
+        ASSERT_EQUALS(1, values.back().intvalue);
+
         // function call => calculation
         code  = "void f(int x) {\n"
                 "    a = x + 8;\n"