diff --git a/lib/checknullpointer.cpp b/lib/checknullpointer.cpp
index 5669f506c..3e53906ac 100644
--- a/lib/checknullpointer.cpp
+++ b/lib/checknullpointer.cpp
@@ -883,7 +883,7 @@ void CheckNullPointer::nullConstantDereference()
             else if (Token::simpleMatch(tok->previous(), ">> 0")) { // Only checking input stream operations is safe here, because otherwise 0 can be an integer as well
                 const Token* tok2 = tok->previous(); // Find start of statement
                 for (; tok2; tok2 = tok2->previous()) {
-                    if (Token::Match(tok2->previous(), ";|{|}|:"))
+                    if (Token::Match(tok2->previous(), ";|{|}|:|("))
                         break;
                 }
                 if (Token::simpleMatch(tok2, "std :: cin"))
@@ -1064,4 +1064,3 @@ void CheckNullPointer::nullPointerDefaultArgError(const Token *tok, const std::s
 {
     reportError(tok, Severity::warning, "nullPointer", "Possible null pointer dereference if the default parameter value is used: " + varname);
 }
-
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index b69afe1cb..58d09cb95 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -2132,6 +2132,15 @@ private:
               "    std::cout << i;\n" // Its no char* (#4240)
               "}", true);
         ASSERT_EQUALS("", errout.str());
+
+        // #5811 false postive: (error) Null pointer dereference
+        check("using namespace std;\n"
+              "std::string itoip(int ip) {\n"
+              "    stringstream out;\n"
+              "    out << ((ip >> 0) & 0xFF);\n"
+              "    return out.str();\n"
+              "}n", true, "test.cpp", false);
+        ASSERT_EQUALS("", errout.str());
     }
 
     void functioncall() {    // #3443 - function calls