diff --git a/lcl/interfaces/qt/qtwinapi.inc b/lcl/interfaces/qt/qtwinapi.inc
index 94a01cddb9..78ab3f95db 100644
--- a/lcl/interfaces/qt/qtwinapi.inc
+++ b/lcl/interfaces/qt/qtwinapi.inc
@@ -1210,10 +1210,10 @@ begin
   if Flags and DT_SINGLELINE <> 0 then
     F := F or QtTextSingleLine;
 
-  if Flags and DT_NOPREFIX = 0 then
+  if Flags and DT_NOPREFIX <> 0 then
     F := F or QtTextShowMnemonic;
 
-  if Flags and DT_NOCLIP = 0 then
+  if Flags and DT_NOCLIP <> 0 then
     F := F or QtTextDontClip;
 
   if Flags and DT_EXPANDTABS <> 0 then