diff --git a/src/plugins/debugger/breakhandler.cpp b/src/plugins/debugger/breakhandler.cpp
index f37dd9b442d3338d00a35023a5273911e4119269..888bf09cc5838d222253d63c0bc0e81ccc1d0246 100644
--- a/src/plugins/debugger/breakhandler.cpp
+++ b/src/plugins/debugger/breakhandler.cpp
@@ -312,8 +312,11 @@ int BreakHandler::findBreakpoint(const QString &fileName, int lineNumber)
 
 int BreakHandler::findBreakpoint(int bpNumber)
 {
+    if (!size())
+        return -1;
+    QString numStr = QString::number(bpNumber);
     for (int index = 0; index != size(); ++index)
-        if (at(index)->bpNumber == QString::number(bpNumber))
+        if (at(index)->bpNumber == numStr)
             return index;
     return -1;
 }