diff --git a/Tests/SystemInformation/DumpInformation.cxx b/Tests/SystemInformation/DumpInformation.cxx
index ebf984bd93..c84af37294 100644
--- a/Tests/SystemInformation/DumpInformation.cxx
+++ b/Tests/SystemInformation/DumpInformation.cxx
@@ -4,6 +4,8 @@
 
 void cmDumpInformationPrintFile(const char* name, FILE* fout)
 {
+  fprintf(fout,
+          "Avoid ctest truncation of output: CTEST_FULL_OUTPUT\n");
   fprintf(fout,
           "================================================================\n");
   struct stat fs;