diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 040b88ed41e..32b9c921e73 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -737,15 +737,21 @@ void SymbolDatabase::createSymbolDatabaseFindAllScopes()
                 } else {
                     tok = tok->link();
                 }
-            } else if (Token::Match(tok, "%name% (")) {
-                if (Token::simpleMatch(tok->linkAt(1), ") ;")) {
+            } else if (Token::Match(tok, "extern %type%")) {
+                const Token * ftok = tok->next();
+                while (Token::Match(ftok, "%name%|*|&"))
+                    ftok = ftok->next();
+                if (!ftok || ftok->str() != "(")
+                    continue;
+                ftok = ftok->previous();
+                if (Token::simpleMatch(ftok->linkAt(1), ") ;")) {
                     const Token *funcStart = nullptr;
                     const Token *argStart = nullptr;
                     const Token *declEnd = nullptr;
-                    if (isFunction(tok, scope, &funcStart, &argStart, &declEnd)) {
+                    if (isFunction(ftok, scope, &funcStart, &argStart, &declEnd)) {
                         if (declEnd && declEnd->str() == ";") {
                             bool newFunc = true; // Is this function already in the database?
-                            auto range = scope->functionMap.equal_range(tok->str());
+                            auto range = scope->functionMap.equal_range(ftok->str());
                             for (std::multimap<std::string, const Function*>::const_iterator it = range.first; it != range.second; ++it) {
                                 if (it->second->argsMatch(scope, it->second->argDef, argStart, emptyString, 0)) {
                                     newFunc = false;
@@ -754,13 +760,12 @@ void SymbolDatabase::createSymbolDatabaseFindAllScopes()
                             }
                             // save function prototype in database
                             if (newFunc) {
-                                Function function(tok, scope, funcStart, argStart);
+                                Function function(ftok, scope, funcStart, argStart);
                                 if (function.isExtern()) {
                                     scope->addFunction(std::move(function));
                                     tok = declEnd;
                                 }
                             }
-                            continue;
                         }
                     }
                 }
@@ -5930,8 +5935,7 @@ const Function* SymbolDatabase::findFunction(const Token* const tok) const
     const Scope *currScope = tok->scope();
     while (currScope && currScope->isExecutable()) {
         if (const Function* f = currScope->findFunction(tok)) {
-            if (f->isExtern())
-                return f;
+            return f;
         }
         if (currScope->functionOf)
             currScope = currScope->functionOf;
diff --git a/test/testsymboldatabase.cpp b/test/testsymboldatabase.cpp
index 7a4c7622b0c..1c42d76fdf9 100644
--- a/test/testsymboldatabase.cpp
+++ b/test/testsymboldatabase.cpp
@@ -270,7 +270,8 @@ class TestSymbolDatabase : public TestFixture {
         TEST_CASE(memberFunctionOfUnknownClassMacro2);
         TEST_CASE(memberFunctionOfUnknownClassMacro3);
         TEST_CASE(functionLinkage);
-        TEST_CASE(externalFunctionsInsideAFunction); // #12420
+        TEST_CASE(externalFunctionsInsideAFunction);    // #12420
+        TEST_CASE(namespacedFunctionInsideExternBlock); // #12420
 
         TEST_CASE(classWithFriend);
 
@@ -2378,6 +2379,20 @@ class TestSymbolDatabase : public TestFixture {
         ASSERT(call && call->function() == f->function());
     }
 
+    void namespacedFunctionInsideExternBlock() {
+        // Should not crash
+        GET_SYMBOL_DB("namespace N {\n"
+                      "    void f();\n"
+                      "}\n"
+                      "extern \"C\" {\n"
+                      "    void f() {\n"
+                      "        N::f();\n"
+                      "    }\n"
+                      "}\n");
+
+        ASSERT(db && errout.str().empty());
+    }
+
     void classWithFriend() {
         GET_SYMBOL_DB("class Foo {}; class Bar1 { friend class Foo; }; class Bar2 { friend Foo; };");
         // 3 scopes: Global, 3 classes