diff --git a/apps/openmw/mwgui/waitdialog.cpp b/apps/openmw/mwgui/waitdialog.cpp
index f74b06891..94905dd9e 100644
--- a/apps/openmw/mwgui/waitdialog.cpp
+++ b/apps/openmw/mwgui/waitdialog.cpp
@@ -155,8 +155,9 @@ namespace MWGui
                 if (!region->mSleepList.empty())
                 {
                     // figure out if player will be woken while sleeping
+                    int x = OEngine::Misc::Rng::rollDice(hoursToWait);
                     float fSleepRandMod = world->getStore().get<ESM::GameSetting>().find("fSleepRandMod")->getFloat();
-                    if (OEngine::Misc::Rng::rollProbability() > fSleepRandMod)
+                    if (x > fSleepRandMod * hoursToWait)
                     {
                         float fSleepRestMod = world->getStore().get<ESM::GameSetting>().find("fSleepRestMod")->getFloat();
                         mInterruptAt = hoursToWait - int(fSleepRestMod * hoursToWait);