diff --git a/krusader/Panel/krpreviewjob.cpp b/krusader/Panel/krpreviewjob.cpp
--- a/krusader/Panel/krpreviewjob.cpp
+++ b/krusader/Panel/krpreviewjob.cpp
@@ -31,7 +31,7 @@
 // QtWidgets
 #include <QWidget>
 
-#define ASSERT(what) if(!what) abort();
+#define ASSERT(what) if(!(what)) abort();
 
 // how much items to process by a single job
 // view becomes unresponsive during load if set too high
@@ -94,7 +94,7 @@
 
 void KrPreviewJob::slotStartJob()
 {
-    ASSERT(_job == 0);
+    ASSERT(_job == nullptr);
     ASSERT(!_scheduled.isEmpty());
 
     _hash.clear();
diff --git a/krusader/Panel/krpreviews.cpp b/krusader/Panel/krpreviews.cpp
--- a/krusader/Panel/krpreviews.cpp
+++ b/krusader/Panel/krpreviews.cpp
@@ -29,7 +29,7 @@
 
 #include <stdio.h>
 
-#define ASSERT(what) if(!what) abort();
+#define ASSERT(what) if(!(what)) abort();
 
 
 KrPreviews::KrPreviews(KrView *view) :  _job(nullptr), _view(view)