diff --git a/lib/checkbufferoverrun.cpp b/lib/checkbufferoverrun.cpp
index 4a8551a15..94ebd95b2 100644
--- a/lib/checkbufferoverrun.cpp
+++ b/lib/checkbufferoverrun.cpp
@@ -841,7 +841,7 @@ void CheckBufferOverrun::checkScope(const Token *tok, const ArrayInfo &arrayInfo
                 valueFlowCheckArrayIndex(tok->next(), arrayInfo);
             }
 
-            else if (isPortabilityEnabled && tok->astParent() && tok->astParent()->str() == "+") {
+            else if (isPortabilityEnabled && !tok->isCasted() && tok->astParent() && tok->astParent()->str() == "+") {
                 const ValueFlow::Value *index;
                 if (tok == tok->astParent()->astOperand1())
                     index = tok->astParent()->astOperand2()->getMaxValue(false);
diff --git a/lib/token.h b/lib/token.h
index 010024267..1ede4fdb4 100644
--- a/lib/token.h
+++ b/lib/token.h
@@ -313,6 +313,12 @@ public:
     void isExpandedMacro(bool m) {
         setFlag(fIsExpandedMacro, m);
     }
+    bool isCasted() const {
+        return getFlag(fIsCasted);
+    }
+    void isCasted(bool c) {
+        setFlag(fIsCasted, c);
+    }
     bool isAttributeConstructor() const {
         return getFlag(fIsAttributeConstructor);
     }
@@ -753,14 +759,15 @@ private:
         fIsLong                 = (1 << 3),
         fIsStandardType         = (1 << 4),
         fIsExpandedMacro        = (1 << 5),
-        fIsAttributeConstructor = (1 << 6),  // __attribute__((constructor)) __attribute__((constructor(priority)))
-        fIsAttributeDestructor  = (1 << 7),  // __attribute__((destructor))  __attribute__((destructor(priority)))
-        fIsAttributeUnused      = (1 << 8),  // __attribute__((unused))
-        fIsAttributePure        = (1 << 9),  // __attribute__((pure))
-        fIsAttributeConst       = (1 << 10), // __attribute__((const))
-        fIsAttributeNothrow     = (1 << 11), // __attribute__((nothrow))
-        fIsDeclspecNothrow      = (1 << 12), // __declspec(nothrow)
-        fIsAttributeUsed        = (1 << 13)  // __attribute__((used))
+        fIsCasted               = (1 << 6),
+        fIsAttributeConstructor = (1 << 7),  // __attribute__((constructor)) __attribute__((constructor(priority)))
+        fIsAttributeDestructor  = (1 << 8),  // __attribute__((destructor))  __attribute__((destructor(priority)))
+        fIsAttributeUnused      = (1 << 9),  // __attribute__((unused))
+        fIsAttributePure        = (1 << 10), // __attribute__((pure))
+        fIsAttributeConst       = (1 << 11), // __attribute__((const))
+        fIsAttributeNothrow     = (1 << 12), // __attribute__((nothrow))
+        fIsDeclspecNothrow      = (1 << 13), // __declspec(nothrow)
+        fIsAttributeUsed        = (1 << 14)  // __attribute__((used))
     };
 
     unsigned int _flags;
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 4f1b776ea..c05b2756e 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -5004,6 +5004,7 @@ void Tokenizer::simplifyCasts()
             if (!tok->tokAt(2)->isUnsigned() && bits > 0)
                 bits--;
             if (bits < 31 && value >= 0 && value < (1LL << bits)) {
+                tok->linkAt(1)->next()->isCasted(true);
                 Token::eraseTokens(tok, tok->next()->link()->next());
             }
             continue;
@@ -5023,6 +5024,15 @@ void Tokenizer::simplifyCasts()
             // Remove cast..
             Token::eraseTokens(tok, tok->next()->link()->next());
 
+            // Set isCasted flag.
+            Token *tok2 = tok->next();
+            if (!Token::Match(tok2, "%var% [|."))
+                tok2->isCasted(true);
+            else {
+                // TODO: handle more complex expressions
+                tok2->next()->isCasted(true);
+            }
+
             // Remove '* &'
             if (Token::simpleMatch(tok, "* &")) {
                 tok->deleteNext();
@@ -5038,6 +5048,7 @@ void Tokenizer::simplifyCasts()
 
         // Replace pointer casts of 0.. "(char *)0" => "0"
         while (Token::Match(tok->next(), "( %type% %type%| * ) 0")) {
+            tok->linkAt(1)->next()->isCasted(true);
             Token::eraseTokens(tok, tok->next()->link()->next());
             if (tok->str() == ")" && tok->link()->previous()) {
                 // If there was another cast before this, go back
@@ -5048,11 +5059,11 @@ void Tokenizer::simplifyCasts()
 
         if (Token::Match(tok->next(), "dynamic_cast|reinterpret_cast|const_cast|static_cast <")) {
             Token *tok2 = tok->linkAt(2);
-
-            if (Token::simpleMatch(tok2, "> ("))
-                Token::eraseTokens(tok, tok2->next());
-            else
+            if (!Token::simpleMatch(tok2, "> ("))
                 break;
+
+            tok2->tokAt(2)->isCasted(true);
+            Token::eraseTokens(tok, tok2->next());
         }
     }
 }
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index 6b0b96fe8..5f12c9ef0 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -2955,6 +2955,12 @@ private:
               "    return a + 100;\n"
               "}");
         ASSERT_EQUALS("[test.cpp:3]: (portability) Undefined behaviour: Pointer arithmetic result does not point into or just past the end of the array.\n", errout.str());
+
+        check("void f() {\n" // #6350 - fp when there is cast of buffer
+              "  wchar_t buf[64];\n"
+              "  p = (unsigned char *) buf + sizeof (buf);\n"
+              "}", false, "6350.c", false);
+        ASSERT_EQUALS("", errout.str());
     }
 
     void pointer_out_of_bounds_2() {