diff --git a/src/tools/moc/generator.cpp b/src/tools/moc/generator.cpp
index 50da6d2..286ce05 100644
--- a/src/tools/moc/generator.cpp
+++ b/src/tools/moc/generator.cpp
@@ -310,9 +310,9 @@ void Generator::generateCode()
                 int escapeLen = lengthOfEscapeSequence(s, backSlashPos);
                 spanLen = qBound(spanLen, backSlashPos + escapeLen - idx, s.length() - idx);
             }
-            fwrite(s.constData() + idx, 1, spanLen, out);
-            idx += spanLen;
-            col += spanLen;
+            auto ret = fwrite(s.constData() + idx, 1, spanLen, out);
+            idx += ret;
+            col += ret;
         }

         fputs("\\0", out);