diff --git a/src/corelib/tools/qtools_p.h b/src/corelib/tools/qtools_p.h
index 338f89d6338..2058f6349e7 100644
--- a/src/corelib/tools/qtools_p.h
+++ b/src/corelib/tools/qtools_p.h
@@ -54,6 +54,11 @@ constexpr inline char toAsciiLower(char ch) noexcept
     return (ch >= 'A' && ch <= 'Z') ? ch - 'A' + 'a' : ch;
 }
 
+constexpr inline char toAsciiUpper(char ch) noexcept
+{
+    return (ch >= 'a' && ch <= 'z') ? ch - 'a' + 'A' : ch;
+}
+
 constexpr inline int caseCompareAscii(char lhs, char rhs) noexcept
 {
     const char lhsLower = QtMiscUtils::toAsciiLower(lhs);
diff --git a/src/tools/moc/moc.h b/src/tools/moc/moc.h
index 843a684bda7..af2a95c3915 100644
--- a/src/tools/moc/moc.h
+++ b/src/tools/moc/moc.h
@@ -13,7 +13,8 @@
 #include <qjsonobject.h>
 #include <qversionnumber.h>
 #include <stdio.h>
-#include <ctype.h>
+
+#include <private/qtools_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -102,7 +103,7 @@ struct PropertyDef
 {
     bool stdCppSet() const {
         QByteArray s("set");
-        s += toupper(name[0]);
+        s += QtMiscUtils::toAsciiUpper(name[0]);
         s += name.mid(1);
         return (s == write);
     }