diff --git a/src/frontends/qt/GuiFontMetrics.cpp b/src/frontends/qt/GuiFontMetrics.cpp
index b3d37caaf1..c227c28d25 100644
--- a/src/frontends/qt/GuiFontMetrics.cpp
+++ b/src/frontends/qt/GuiFontMetrics.cpp
@@ -603,7 +603,7 @@ GuiFontMetrics::breakString_helper(docstring const & s, int first_wid, int wid,
 		// FIXME: this is slower than it could be but we'll get rid of Qt4 anyway
 		docstring const ss = s.substr(pos, epos - pos);
 		int const wid = width(ss);
-		int const nspc_wid = i + 1 < tl.lineCount() ? wid : width(rtrim(ss));
+		int const nspc_wid = i + 1 < tl.lineCount() ? width(rtrim(ss)) : wid;
 #endif
 		breaks.emplace_back(epos - pos, wid, nspc_wid);
 		pos = epos;