diff --git a/src/flags/flag-definitions.h b/src/flags/flag-definitions.h
index 3e27c1d9d3..7222b334ff 100644
--- a/src/flags/flag-definitions.h
+++ b/src/flags/flag-definitions.h
@@ -713,7 +713,7 @@ DEFINE_BOOL(baseline_batch_compilation, true, "batch compile Sparkplug code")
 DEFINE_BOOL_READONLY(concurrent_sparkplug, false,
                      "compile Sparkplug code in a background thread")
 #else
-DEFINE_BOOL(concurrent_sparkplug, true,
+DEFINE_BOOL(concurrent_sparkplug, false,
             "compile Sparkplug code in a background thread")
 DEFINE_WEAK_IMPLICATION(future, concurrent_sparkplug)
 DEFINE_NEG_IMPLICATION(predictable, concurrent_sparkplug)
@@ -721,7 +721,7 @@ DEFINE_NEG_IMPLICATION(single_threaded, concurrent_sparkplug)
 DEFINE_NEG_IMPLICATION(jitless, concurrent_sparkplug)
 #endif
 DEFINE_UINT(
-    concurrent_sparkplug_max_threads, 2,
+    concurrent_sparkplug_max_threads, 0,
     "max number of threads that concurrent Sparkplug can use (0 for unbounded)")
 #else
 DEFINE_BOOL(baseline_batch_compilation, false, "batch compile Sparkplug code")