diff --git a/src/corelib/tools/qbytearray.cpp b/src/corelib/tools/qbytearray.cpp
index a6bb6afe57..32834ebd7e 100644
--- a/src/corelib/tools/qbytearray.cpp
+++ b/src/corelib/tools/qbytearray.cpp
@@ -3886,7 +3886,7 @@ QByteArray QByteArray::fromRawData(const char *data, int size)
     } else if (!size) {
         x = shared_empty.data_ptr();
     } else {
-        x = static_cast<Data *>(malloc(sizeof(Data) + 1));
+        x = static_cast<Data *>(malloc(sizeof(Data)));
         Q_CHECK_PTR(x);
         x->ref.initializeOwned();
         x->size = size;
diff --git a/src/corelib/tools/qstring.cpp b/src/corelib/tools/qstring.cpp
index 5e69a13057..710aec931a 100644
--- a/src/corelib/tools/qstring.cpp
+++ b/src/corelib/tools/qstring.cpp
@@ -7438,7 +7438,7 @@ QString QString::fromRawData(const QChar *unicode, int size)
     } else if (!size) {
         x = shared_empty.data_ptr();
     } else {
-        x = static_cast<Data *>(::malloc(sizeof(Data) + sizeof(ushort)));
+        x = static_cast<Data *>(::malloc(sizeof(Data)));
         Q_CHECK_PTR(x);
         x->ref.initializeOwned();
         x->size = size;