diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
index 0f2da221483..3ecb52c0b36 100644
--- a/src/backend/executor/instrument.c
+++ b/src/backend/executor/instrument.c
@@ -63,7 +63,7 @@ void
 InstrStartNode(Instrumentation *instr)
 {
 	if (instr->need_timer &&
-		INSTR_TIME_SET_CURRENT_LAZY(instr->starttime))
+		!INSTR_TIME_SET_CURRENT_LAZY(instr->starttime))
 		elog(ERROR, "InstrStartNode called twice in a row");
 
 	/* save buffer usage totals at node entry, if needed */