diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index caea334e5..c6e2c1b88 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -9463,15 +9463,27 @@ void Tokenizer::simplifyNamespaceStd()
 
     const bool isCPP11  = mSettings->standards.cpp == Standards::CPP11;
 
+    std::set<std::string> userFunctions;
+
     for (const Token* tok = Token::findsimplematch(list.front(), "using namespace std ;"); tok; tok = tok->next()) {
         bool insert = false;
         if (Token::Match(tok, "enum class|struct| %name%| :|{")) { // Don't replace within enum definitions
             skipEnumBody(&tok);
         }
         if (!Token::Match(tok->previous(), ".|::")) {
-            if (Token::Match(tok, "%name% (") && !isFunctionHead(tok->next(),"{") && stdFunctions.find(tok->str()) != stdFunctions.end())
-                insert = true;
-            else if (Token::Match(tok, "%name% <") && stdTemplates.find(tok->str()) != stdTemplates.end())
+            if (Token::Match(tok, "%name% (")) {
+                if (isFunctionHead(tok->next(), "{"))
+                    userFunctions.insert(tok->str());
+                else if (isFunctionHead(tok->next(), ";")) {
+                    const Token *start = tok;
+                    while (Token::Match(start->previous(), "%type%|*|&"))
+                        start = start->previous();
+                    if (start != tok && start->isName() && (!start->previous() || Token::Match(start->previous(), "[;{}]")))
+                        userFunctions.insert(tok->str());
+                }
+                if (userFunctions.find(tok->str()) == userFunctions.end() && stdFunctions.find(tok->str()) != stdFunctions.end())
+                    insert = true;
+            } else if (Token::Match(tok, "%name% <") && stdTemplates.find(tok->str()) != stdTemplates.end())
                 insert = true;
             else if (tok->isName() && !tok->varId() && !Token::Match(tok->next(), "(|<") && stdTypes.find(tok->str()) != stdTypes.end())
                 insert = true;
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 47bf0db7a..04eb9a0cd 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -5633,6 +5633,11 @@ private:
                "void search() {}";
         ASSERT_EQUALS("void search ( ) { }", tokenizeAndStringify(code, false));
 
+        code = "using namespace std;\n"
+               "void search();\n"
+               "void dostuff() { search(); }";
+        ASSERT_EQUALS("void search ( ) ;\nvoid dostuff ( ) { search ( ) ; }", tokenizeAndStringify(code, false));
+
         code = "using namespace std;\n"
                "void foo() {map(a, b); }"; // That's obviously not std::map<>
         ASSERT_EQUALS("void foo ( ) { map ( a , b ) ; }", tokenizeAndStringify(code, false));