fix an error

Change-Id: I2e65ab7c54a1620aba42d59b4e797eb4c6cacb9c
diff --git a/src/configuration.cpp b/src/configuration.cpp
index 09b5f68..f53ebda 100644
--- a/src/configuration.cpp
+++ b/src/configuration.cpp
@@ -55,7 +55,7 @@
   // CA max suffix length
   m_maxSuffixLength = nullopt;
   auto maxSuffixLength = configJson.get_optional<size_t>(CONFIG_MAX_SUFFIX_LENGTH);
-  if (maxSuffixLength.has_value()) {
+  if (maxSuffixLength) {
     m_maxSuffixLength = *maxSuffixLength;
   }
   // probe parameter keys