diff --git a/compiler-rt/test/fuzzer/merge-posix.test b/compiler-rt/test/fuzzer/merge-posix.test
index 2721668fb9706..5e342142216f8 100644
--- a/compiler-rt/test/fuzzer/merge-posix.test
+++ b/compiler-rt/test/fuzzer/merge-posix.test
@@ -14,7 +14,7 @@ RUN: echo ....U. > %tmp/T2/2
 RUN: echo ...Z.. > %tmp/T2/3
 RUN: echo ...Z.. > %tmp/T2/4
 RUN: echo ....E. > %tmp/T2/5
-RUN: echo .....R > %tmp/T2/6
+RUN: %python -c "print('.....R' + 'X' * 1024, end='')" > %tmp/T2/6
 
 # Check that we can report an error if file size exceeded
 RUN: (ulimit -f 1; not %run %t-FullCoverageSetTest -merge=1 %tmp/T1 %tmp/T2 2>&1 | FileCheck %s --check-prefix=SIGXFSZ)