diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index d61b06f21..b2dd2a65d 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -1675,6 +1675,8 @@ bool Tokenizer::tokenize(std::istream &code,
     if (!simplifyAddBraces())
         return false;
 
+    sizeofAddParentheses();
+
     // Combine tokens..
     combineOperators();
 
@@ -3207,6 +3209,42 @@ void Tokenizer::createLinks2()
     }
 }
 
+void Tokenizer::sizeofAddParentheses()
+{
+    for (Token *tok = list.front(); tok; tok = tok->next()) {
+        if (Token::Match(tok, "sizeof %var%")) {
+            Token *tempToken = tok->next();
+            while (Token::Match(tempToken, "%var%")) {
+                while (tempToken && tempToken->next() && tempToken->next()->str() == "[")
+                    tempToken = tempToken->next()->link();
+                if (!tempToken || !tempToken->next())
+                    break;
+
+                if (Token::Match(tempToken->next(), ". %var%")) {
+                    // We are checking a class or struct, search next varname
+                    tempToken = tempToken->tokAt(2);
+                    continue;
+                } else if (tempToken->next()->type() == Token::eIncDecOp) {
+                    // We have variable++ or variable--, the sizeof argument
+                    // ends after the op
+                    tempToken = tempToken->next();
+                } else if (Token::Match(tempToken->next(), "[),;}]")) {
+                    ;
+                } else {
+                    break;
+                }
+
+                // Ok. Add ( after sizeof and ) after tempToken
+                tok->insertToken("(");
+                tempToken->insertToken(")");
+                Token::createMutualLinks(tok->next(), tempToken->next());
+                break;
+            }
+        }
+    }
+
+}
+
 bool Tokenizer::simplifySizeof()
 {
     // Locate variable declarations and calculate the size
diff --git a/lib/tokenize.h b/lib/tokenize.h
index 9842012b4..a98bc8e1b 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -196,6 +196,9 @@ public:
       */
     void simplifyRealloc();
 
+    /** Add parentheses for sizeof: sizeof x => sizeof(x) */
+    void sizeofAddParentheses();
+
     /**
      * Replace sizeof() to appropriate size.
      * @return true if modifications to token-list are done.
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index 5e45039d2..404082962 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -803,6 +803,13 @@ private:
               "}", true, "test.cpp", false);
         ASSERT_EQUALS("", errout.str());
 
+        check("void f(type* p) {\n" // #4983
+              "    x(sizeof p[0]);\n"
+              "    if (!p)\n"
+              "        ;\n"
+              "}", false, "test.cpp", false);
+        ASSERT_EQUALS("", errout.str());
+
         // #3023 - checked deref
         check("void f(struct ABC *abc) {\n"
               "  WARN_ON(!abc || abc->x == 0);\n"
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 327a8bf37..83580a3c5 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -579,7 +579,7 @@ private:
 
     void tokenize2() {
         const std::string code("{ sizeof a, sizeof b }");
-        ASSERT_EQUALS("{ sizeof a , sizeof b }", tokenizeAndStringify(code.c_str()));
+        ASSERT_EQUALS("{ sizeof ( a ) , sizeof ( b ) }", tokenizeAndStringify(code.c_str()));
     }
 
     void tokenize3() {