diff --git a/Libraries/LibJS/Runtime/StringPrototype.cpp b/Libraries/LibJS/Runtime/StringPrototype.cpp
index 3da7fbe542..87a5f58b50 100644
--- a/Libraries/LibJS/Runtime/StringPrototype.cpp
+++ b/Libraries/LibJS/Runtime/StringPrototype.cpp
@@ -118,7 +118,9 @@ Value StringPrototype::repeat(Interpreter& interpreter)
         return interpreter.throw_exception<RangeError>("repeat count must be a positive number");
     if (count_value.is_infinity())
         return interpreter.throw_exception<RangeError>("repeat count must be a finite number");
-    auto count = count_value.as_size_t();
+    auto count = count_value.to_size_t(interpreter);
+    if (interpreter.exception())
+        return {};
     StringBuilder builder;
     for (size_t i = 0; i < count; ++i)
         builder.append(string);
diff --git a/Libraries/LibJS/Runtime/Value.cpp b/Libraries/LibJS/Runtime/Value.cpp
index 194998d903..7c19e5529b 100644
--- a/Libraries/LibJS/Runtime/Value.cpp
+++ b/Libraries/LibJS/Runtime/Value.cpp
@@ -250,8 +250,6 @@ i32 Value::as_i32() const
 size_t Value::as_size_t() const
 {
     ASSERT(as_double() >= 0);
-    if (is_nan())
-        return 0;
     return min((double)(i32)as_double(), MAX_ARRAY_LIKE_INDEX);
 }
 
@@ -278,7 +276,9 @@ size_t Value::to_size_t(Interpreter& interpreter) const
     auto number = to_number(interpreter);
     if (interpreter.exception())
         return 0;
-    if (as_double() <= 0)
+    if (number.is_nan())
+        return 0;
+    if (number.as_double() <= 0)
         return 0;
     return number.as_size_t();
 }