diff --git a/lib/checkother.cpp b/lib/checkother.cpp
index 282f3f3e50e..09b94d97baa 100644
--- a/lib/checkother.cpp
+++ b/lib/checkother.cpp
@@ -2663,6 +2663,14 @@ isStaticAssert(const Settings &settings, const Token *tok)
     return false;
 }
 
+static bool isSizeof(const Token *tok)
+{
+    if (!Token::simpleMatch(tok, "("))
+        return false;
+
+    return Token::simpleMatch(tok->astOperand1(), "sizeof");
+}
+
 void CheckOther::checkDuplicateExpression()
 {
     {
@@ -2846,7 +2854,8 @@ void CheckOther::checkDuplicateExpression()
             } else if (tok->astOperand1() && tok->astOperand2() && tok->str() == ":" && tok->astParent() && tok->astParent()->str() == "?") {
                 if (!tok->astOperand1()->values().empty() && !tok->astOperand2()->values().empty() && isEqualKnownValue(tok->astOperand1(), tok->astOperand2()) &&
                     !isVariableChanged(tok->astParent(), /*indirect*/ 0, *mSettings) &&
-                    isConstStatement(tok->astOperand1(), mSettings->library) && isConstStatement(tok->astOperand2(), mSettings->library))
+                    isConstStatement(tok->astOperand1(), mSettings->library) && isConstStatement(tok->astOperand2(), mSettings->library) &&
+                    !isSizeof(tok->astOperand1()) && !isSizeof(tok->astOperand2()))
                     duplicateValueTernaryError(tok);
                 else if (isSameExpression(true, tok->astOperand1(), tok->astOperand2(), *mSettings, false, true, &errorPath))
                     duplicateExpressionTernaryError(tok, std::move(errorPath));
diff --git a/test/testother.cpp b/test/testother.cpp
index 492f111e10e..eb6bb28b060 100644
--- a/test/testother.cpp
+++ b/test/testother.cpp
@@ -306,6 +306,8 @@ class TestOther : public TestFixture {
 
         TEST_CASE(knownConditionFloating);
         TEST_CASE(knownConditionPrefixed);
+
+        TEST_CASE(ternarySameValueSizeof); // #13773
     }
 
 #define check(...) check_(__FILE__, __LINE__, __VA_ARGS__)
@@ -13093,6 +13095,19 @@ class TestOther : public TestFixture {
             "[test.cpp:2:13] -> [test.cpp:3:11]: (style) The comparison 'i > +1' is always false. [knownConditionTrueFalse]\n",
             errout_str());
     }
+
+    void ternarySameValueSizeof() // #13773
+    {
+        check("void f(void) {\n"
+              "    b = a ? sizeof(unsigned int) : sizeof(uint32_t);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
+
+        check("void f(void) {\n"
+              "    b = a ? sizeof(uint32_t) : sizeof(uint32_t);\n"
+              "}\n");
+        ASSERT_EQUALS("[test.cpp:2:30]: (style) Same expression in both branches of ternary operator. [duplicateExpressionTernary]\n", errout_str());
+    }
 };
 
 REGISTER_TEST(TestOther)