diff --git a/tracing-subscriber/src/registry/extensions.rs b/tracing-subscriber/src/registry/extensions.rs
index ea20d94095..899e1549f7 100644
--- a/tracing-subscriber/src/registry/extensions.rs
+++ b/tracing-subscriber/src/registry/extensions.rs
@@ -120,6 +120,7 @@ pub(crate) struct ExtensionsInner {
 
 impl ExtensionsInner {
     /// Create an empty `Extensions`.
+    #[cfg(any(test, feature = "registry"))]
     #[inline]
     #[cfg(any(test, feature = "registry"))]
     pub(crate) fn new() -> ExtensionsInner {