diff --git a/src/Autopilot/route_mgr.cxx b/src/Autopilot/route_mgr.cxx
index 1530497e8..127e2c397 100644
--- a/src/Autopilot/route_mgr.cxx
+++ b/src/Autopilot/route_mgr.cxx
@@ -1128,7 +1128,7 @@ void FGRouteMgr::loadRoute()
     
   try {
     readProperties(path.str(), routeData);
-  } catch (sg_exception& e) {
+  } catch (sg_exception& ) {
     // if XML parsing fails, the file might be simple textual list of waypoints
     loadPlainTextRoute(path);
     return;
diff --git a/src/GUI/dialog.cxx b/src/GUI/dialog.cxx
index 8a4160499..71d6d7279 100644
--- a/src/GUI/dialog.cxx
+++ b/src/GUI/dialog.cxx
@@ -369,7 +369,7 @@ void fgPopup::applySize(puObject *object)
 void FGDialog::ConditionalObject::update(FGDialog* aDlg)
 {
   if (_name == "visible") {
-    bool wasVis = _pu->isVisible();
+    bool wasVis = _pu->isVisible() != 0;
     bool newVis = test();
     
     if (newVis == wasVis) {
@@ -382,7 +382,7 @@ void FGDialog::ConditionalObject::update(FGDialog* aDlg)
       _pu->hide();
     }
   } else if (_name == "enable") {
-    bool wasEnabled = _pu->isActive();
+    bool wasEnabled = _pu->isActive() != 0;
     bool newEnable = test();
     
     if (wasEnabled == newEnable) {
diff --git a/src/Navaids/route.cxx b/src/Navaids/route.cxx
index 613e5b3c4..580c87c18 100644
--- a/src/Navaids/route.cxx
+++ b/src/Navaids/route.cxx
@@ -66,7 +66,7 @@ std::string Waypt::ident() const
   
 bool Waypt::flag(WayptFlag aFlag) const
 {
-  return (_flags & aFlag);
+  return ((_flags & aFlag) != 0);
 }
 	
 void Waypt::setFlag(WayptFlag aFlag, bool aV)