diff --git a/flang/lib/parser/features.h b/flang/lib/parser/features.h
index ef8da55f4b69..d4aeef1f741a 100644
--- a/flang/lib/parser/features.h
+++ b/flang/lib/parser/features.h
@@ -30,7 +30,9 @@ using LanguageFeatures = common::EnumSet<LanguageFeature, 32>;
 class LanguageFeatureControl {
 public:
   LanguageFeatureControl() {
+    // These features must be explicitly enabled by command line options.
     disable_.set(LanguageFeature::OldDebugLines);
+    disable_.set(LanguageFeature::OpenMP);
     // These features, if enabled, conflict with valid standard usage.
     disable_.set(LanguageFeature::LogicalAbbreviations);
     disable_.set(LanguageFeature::XOROperator);