diff --git a/lib/checkautovariables.cpp b/lib/checkautovariables.cpp
index 6c68ff6f3..0a1ba0610 100644
--- a/lib/checkautovariables.cpp
+++ b/lib/checkautovariables.cpp
@@ -190,7 +190,7 @@ void CheckAutoVariables::assignFunctionArg()
             // TODO: What happens if this is removed?
             if (tok->astParent())
                 continue;
-            if (!Token::Match(tok, "=|++|--") || !Token::Match(tok->astOperand1(), "%var%"))
+            if (!(tok->isAssignmentOp() || Token::Match(tok, "++|--")) || !Token::Match(tok->astOperand1(), "%var%"))
                 continue;
             const Token* const vartok = tok->astOperand1();
             if (isNonReferenceArg(vartok) &&
diff --git a/test/testautovariables.cpp b/test/testautovariables.cpp
index 552a7e3f2..cc2e082d6 100644
--- a/test/testautovariables.cpp
+++ b/test/testautovariables.cpp
@@ -274,6 +274,11 @@ private:
               "}");
         ASSERT_EQUALS("[test.cpp:2]: (style) Assignment of function parameter has no effect outside the function.\n", errout.str());
 
+        check("void foo(int b) {\n"
+              "    b += 1;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (style) Assignment of function parameter has no effect outside the function.\n", errout.str());
+
         check("void foo(std::string s) {\n"
               "    s = foo(b);\n"
               "}");