diff --git a/clang/test/CAS/validate-once.c b/clang/test/CAS/validate-once.c
index faadebe5ad019..669e0861d226a 100644
--- a/clang/test/CAS/validate-once.c
+++ b/clang/test/CAS/validate-once.c
@@ -1,16 +1,23 @@
 // RUN: rm -rf %t
 
-// RUN: llvm-cas --cas %t/cas --ingest %s
+// RUN: env LLVM_CAS_LOG=2 llvm-cas --cas %t/cas --ingest %s
 // RUN: mv %t/cas/v1.1/v10.data %t/cas/v1.1/v10.data.bak
 
-// RUN: %clang -cc1depscand -execute %{clang-daemon-dir}/%basename_t -cas-args -fcas-path %t/cas -- \
+// RUN: env LLVM_CAS_LOG=2 %clang -cc1depscand -execute %{clang-daemon-dir}/%basename_t -cas-args -fcas-path %t/cas -- \
 // RUN:   %clang -target x86_64-apple-macos11 -I %S/Inputs \
 // RUN:     -Xclang -fcas-path -Xclang %t/cas \
 // RUN:     -fdepscan=daemon -fdepscan-daemon=%{clang-daemon-dir}/%basename_t -fsyntax-only -x c %s
 
 // RUN: ls %t/cas/corrupt.0.v1.1
 
-// RUN: llvm-cas --cas %t/cas --validate-if-needed | FileCheck %s -check-prefix=SKIPPED
+// RUN: env LLVM_CAS_LOG=2 llvm-cas --cas %t/cas --validate-if-needed > %t/output
+
+// Logging is enabled to try to catch a rare failure where validation is not
+// skipped.
+// RUN: cat %t/cas/v1.validation
+// RUN: cat %t/cas/v1.log
+
+// RUN: cat %t/output | FileCheck %s -check-prefix=SKIPPED
 // SKIPPED: validation skipped
 
 #include "test.h"