diff --git a/src/base/tools/String.cpp b/src/base/tools/String.cpp
index f93222746..8187f467a 100644
--- a/src/base/tools/String.cpp
+++ b/src/base/tools/String.cpp
@@ -33,7 +33,7 @@
 xmrig::String::String(const char *str) :
     m_size(str == nullptr ? 0 : strlen(str))
 {
-    if (m_size == 0) {
+    if (str == nullptr) {
         return;
     }