diff --git a/src/gui/painting/qtriangulator.cpp b/src/gui/painting/qtriangulator.cpp
index df96e9f9567..17799cb0727 100644
--- a/src/gui/painting/qtriangulator.cpp
+++ b/src/gui/painting/qtriangulator.cpp
@@ -418,6 +418,7 @@ static inline int primeForNumBits(int numBits)
 
 static inline int primeForCount(int count)
 {
+    Q_ASSERT(count >= 0); // Q_PRE
     int low = 0;
     int high = 32;
     for (int i = 0; i < 5; ++i) {