diff --git a/tests/froll.R b/tests/froll.R
index faf69d28b..d4ca87f9d 100644
--- a/tests/froll.R
+++ b/tests/froll.R
@@ -1,4 +1,10 @@
-Sys.setenv(OMP_THREAD_LIMIT = Sys.getenv("OMP_THREAD_LIMIT", "2"))
+# Valgrind developers say that performing work after fork() without
+# exec() is problematic for Valgrind. frollapply() uses
+# parallel::mcparallel(), which causes Valgrind to run
+# Rstd_ReadConsole() incorrectly.
+Sys.setenv(OMP_THREAD_LIMIT =
+  if (grepl("valgrind", Sys.getenv("LD_PRELOAD"))) "1" else Sys.getenv("OMP_THREAD_LIMIT", "2")
+)
 require(data.table)
 test.data.table(script="froll.Rraw")
 test.data.table(script="frollBatch.Rraw", optional=TRUE)