diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index af2ca4ea432..8eaea623500 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -313,13 +313,26 @@ void CheckOther::warningOldStylePointerCast()
             tok = scope->bodyStart;
         for (; tok && tok != scope->bodyEnd; tok = tok->next()) {
             // Old style pointer casting..
-            if (!Token::Match(tok, "( const|volatile| const|volatile|class|struct| %type% * *| *| const|&| ) (| %name%|%num%|%bool%|%char%|%str%|&"))
+            if (tok->str() != "(")
                 continue;
+            const Token* castTok = tok->next();
+            while (Token::Match(castTok, "const|volatile|class|struct|union|%type%|::")) {
+                castTok = castTok->next();
+                if (Token::simpleMatch(castTok, "<") && castTok->link())
+                    castTok = castTok->link()->next();
+            }
+            if (castTok == tok->next() || !Token::simpleMatch(castTok, "*"))
+                continue;
+            while (Token::Match(castTok, "*|const|&"))
+                castTok = castTok->next();
+            if (!Token::Match(castTok, ") (| %name%|%num%|%bool%|%char%|%str%|&"))
+                continue;
+
             if (Token::Match(tok->previous(), "%type%"))
                 continue;
 
             // skip first "const" in "const Type* const"
-            while (Token::Match(tok->next(), "const|volatile|class|struct"))
+            while (Token::Match(tok->next(), "const|volatile|class|struct|union"))
                 tok = tok->next();
             const Token* typeTok = tok->next();
             // skip second "const" in "const Type* const"
diff --git a/test/testother.cpp b/test/testother.cpp
index 2c949a47877..3f938af2e85 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -1895,6 +1895,22 @@ class TestOther : public TestFixture {
         ASSERT_EQUALS("[test.cpp:2]: (style) C-style pointer casting\n"
                       "[test.cpp:3]: (style) C-style pointer casting\n",
                       errout.str());
+
+        // #12446
+        checkOldStylePointerCast("namespace N { struct S {}; }\n"
+                                 "union U {\n"
+                                 "    int i;\n"
+                                 "    char c[4];\n"
+                                 "};\n"
+                                 "void f(void* p) {\n"
+                                 "    auto ps = (N::S*)p;\n"
+                                 "    auto pu = (union U*)p;\n"
+                                 "    auto pv = (std::vector<int>*)(p);\n"
+                                 "}\n");
+        ASSERT_EQUALS("[test.cpp:7]: (style) C-style pointer casting\n"
+                      "[test.cpp:8]: (style) C-style pointer casting\n"
+                      "[test.cpp:9]: (style) C-style pointer casting\n",
+                      errout.str());
     }
 
 #define checkInvalidPointerCast(...) checkInvalidPointerCast_(__FILE__, __LINE__, __VA_ARGS__)