diff --git a/scripts/tracetool/backend/dtrace.py b/scripts/tracetool/backend/dtrace.py
index b7fe4c1b50..fc0c8fc52f 100644
--- a/scripts/tracetool/backend/dtrace.py
+++ b/scripts/tracetool/backend/dtrace.py
@@ -44,11 +44,15 @@ def generate_h_begin(events, group):
     # require SDT_USE_VARIADIC to be defined. If dtrace includes <sys/sdt.h>
     # first without defining SDT_USE_VARIADIC then ust breaks because the
     # STAP_PROBEV() macro is not defined.
+    out('#ifndef SDT_USE_VARIADIC')
     out('#define SDT_USE_VARIADIC 1')
+    out('#endif')
 
     out('#include "%s"' % header,
         '')
 
+    out('#undef SDT_USE_VARIADIC')
+
     # SystemTap defines <provider>_<name>_ENABLED() but other DTrace
     # implementations might not.
     for e in events:
diff --git a/trace/control.c b/trace/control.c
index 2ffe000818..6558b5c906 100644
--- a/trace/control.c
+++ b/trace/control.c
@@ -225,6 +225,7 @@ void trace_init_file(const char *file)
 {
 #ifdef CONFIG_TRACE_SIMPLE
     st_set_trace_file(file);
+    st_set_trace_file_enabled(true);
 #elif defined CONFIG_TRACE_LOG
     /*
      * If both the simple and the log backends are enabled, "--trace file"