diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index ba6a17b0e..58ffdbf4f 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -1091,14 +1091,14 @@ static Token * valueFlowSetConstantValue(Token *tok, const Settings *settings, b
         } else if (Token::Match(tok, "sizeof ( %var% ) / sizeof (") && tok->next()->astParent() == tok->tokAt(4)) {
             // Get number of elements in array
             const Token *sz1 = tok->tokAt(2);
-            const Token *sz2 = tok->tokAt(7);
+            const Token *sz2 = tok->tokAt(6); // left parenthesis
             const nonneg int varid1 = sz1->varId();
             if (varid1 &&
                 sz1->variable() &&
                 sz1->variable()->isArray() &&
                 !sz1->variable()->dimensions().empty() &&
                 sz1->variable()->dimensionKnown(0) &&
-                (Token::Match(sz2, "* %varid% )", varid1) || Token::Match(sz2, "%varid% [ 0 ] )", varid1))) {
+                Token::Match(sz2->astOperand2(), "*|[") && Token::Match(sz2->astOperand2()->astOperand1(), "%var%", varid1)) {
                 ValueFlow::Value value(sz1->variable()->dimension(0));
                 if (!tok2->isTemplateArg() && settings->platformType != cppcheck::Platform::Unspecified)
                     value.setKnown();
diff --git a/test/testbufferoverrun.cpp b/test/testbufferoverrun.cpp
index 613c62d8a..0f455c52f 100644
--- a/test/testbufferoverrun.cpp
+++ b/test/testbufferoverrun.cpp
@@ -187,6 +187,7 @@ private:
         TEST_CASE(array_index_60); // #10617, #9824
         TEST_CASE(array_index_61); // #10621
         TEST_CASE(array_index_62); // #7684
+        TEST_CASE(array_index_63); // #10979
         TEST_CASE(array_index_multidim);
         TEST_CASE(array_index_switch_in_for);
         TEST_CASE(array_index_for_in_for);   // FP: #2634
@@ -1782,6 +1783,18 @@ private:
                       errout.str());
     }
 
+    void array_index_63()
+    {
+        check("int b[4];\n" // #10979
+              "void f(int i) {\n"
+              "    if (i >= 0 && i < sizeof(b) / sizeof(*(b)))\n"
+              "        b[i] = 0;\n"
+              "    if (i >= 0 && i < sizeof(b) / sizeof((b)[0]))\n"
+              "        b[i] = 0;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void array_index_multidim() {
         check("void f()\n"
               "{\n"