diff --git a/tests/perf/de/bug26338_1 b/tests/perf/de/bug26338_1
index 7292e03e89..85ba0a9cfa 100644
--- a/tests/perf/de/bug26338_1
+++ b/tests/perf/de/bug26338_1
@@ -12,3 +12,9 @@ trinfo result
 chrono s restart
 writestl result $imagedir/${casename}-binary.stl 1
 chrono s stop counter writestl
+set aFileSize [file size $imagedir/${casename}-binary.stl]
+if {$aFileSize < 100000000} {
+  puts "Error: unexpected file size"
+} else {
+  file delete -force $imagedir/${casename}-binary.stl
+}
diff --git a/tests/perf/de/bug26338_2 b/tests/perf/de/bug26338_2
index b4700916d8..57c3170e0c 100644
--- a/tests/perf/de/bug26338_2
+++ b/tests/perf/de/bug26338_2
@@ -11,4 +11,10 @@ trinfo result
 # write to ascii STL
 dchrono s restart
 writestl result $imagedir/${casename}-ascii.stl 0
-dchrono s stop counter writestl
\ No newline at end of file
+dchrono s stop counter writestl
+set aFileSize [file size $imagedir/${casename}-ascii.stl]
+if {$aFileSize < 490000000} {
+  puts "Error: unexpected file size"
+} else {
+  file delete -force $imagedir/${casename}-ascii.stl
+}