diff --git a/api/trace/noop_span.go b/api/trace/noop_span.go
index fe075383d..174bc0810 100644
--- a/api/trace/noop_span.go
+++ b/api/trace/noop_span.go
@@ -23,6 +23,9 @@ import (
 	"github.com/open-telemetry/opentelemetry-go/api/event"
 )
 
+type noopSpan struct {
+}
+
 var _ Span = (*noopSpan)(nil)
 
 // SpancContext returns an invalid span context.
diff --git a/api/trace/noop_trace.go b/api/trace/noop_trace.go
index 29bc5b578..36711f195 100644
--- a/api/trace/noop_trace.go
+++ b/api/trace/noop_trace.go
@@ -21,9 +21,6 @@ import (
 	"github.com/open-telemetry/opentelemetry-go/api/scope"
 )
 
-type noopSpan struct {
-}
-
 type noopTracer struct {
 	resources core.EventID
 }
@@ -72,3 +69,5 @@ func (t *noopTracer) Start(ctx context.Context, name string, opts ...SpanOption)
 // Inject does nothing.
 func (t *noopTracer) Inject(ctx context.Context, span Span, injector Injector) {
 }
+
+var _ Injector = (*noopTracer)(nil)