diff --git a/src/lib/caching/kshareddatacache_p.h b/src/lib/caching/kshareddatacache_p.h
--- a/src/lib/caching/kshareddatacache_p.h
+++ b/src/lib/caching/kshareddatacache_p.h
@@ -472,7 +472,10 @@
         ;
     }
 
-    if (result < 0) {
+    if (result != 0) {
+        if (result == ENOSPC) {
+            qCritical() << "No space left on device. Check filesystem free space at your XDG_CACHE_HOME!";
+        }
         qCritical() << "The operating system is unable to promise"
                     << fileSize
                     << "bytes for mapped cache, "