diff --git a/src/runtime.cc b/src/runtime.cc
index 4e6355c6ae..f82cbf14a7 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -6970,8 +6970,12 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_SparseJoinWithSeparator) {
   // Find total length of join result.
   int string_length = 0;
   bool is_ascii = separator->IsAsciiRepresentation();
-  int max_string_length = is_ascii ? SeqAsciiString::kMaxLength
-                                   : SeqTwoByteString::kMaxLength;
+  int max_string_length;
+  if (is_ascii) {
+    max_string_length = SeqAsciiString::kMaxLength;
+  } else {
+    max_string_length = SeqTwoByteString::kMaxLength;
+  }
   bool overflow = false;
   CONVERT_NUMBER_CHECKED(int, elements_length,
                          Int32, elements_array->length());