diff --git a/prometric-derive/src/expand.rs b/prometric-derive/src/expand.rs
index 3be9db1..1154777 100644
--- a/prometric-derive/src/expand.rs
+++ b/prometric-derive/src/expand.rs
@@ -193,7 +193,7 @@ impl MetricBuilder {
 
         if let MetricType::Histogram(_) = &self.ty {
             let buckets = if let Some(buckets_expr) = buckets {
-                quote! { Some(#buckets_expr) }
+                quote! { Some(#buckets_expr.into()) }
             } else {
                 quote! { None }
             };
diff --git a/prometric-derive/src/lib.rs b/prometric-derive/src/lib.rs
index caee130..34e185f 100644
--- a/prometric-derive/src/lib.rs
+++ b/prometric-derive/src/lib.rs
@@ -153,11 +153,13 @@ mod utils;
 /// the current process.
 ///
 /// ```rust
+/// # #[cfg(feature = "process")] {
 /// use prometric::process::ProcessCollector;
 /// use prometric_derive::metrics;
 ///
 /// let mut collector = ProcessCollector::default();
 /// collector.collect();
+/// # }
 /// ```
 ///
 /// #### Output
diff --git a/prometric-derive/tests/macro.rs b/prometric-derive/tests/macro.rs
index 435a329..7a8472e 100644
--- a/prometric-derive/tests/macro.rs
+++ b/prometric-derive/tests/macro.rs
@@ -193,3 +193,28 @@ fn bucket_expressions_work() {
 
     assert!(output.contains("test_hist"));
 }
+
+#[test]
+fn bucket_defaults_work() {
+    #[prometric_derive::metrics(scope = "test")]
+    struct BucketMetrics {
+        /// Test histogram metric with bucket expression.
+        #[metric]
+        hist: prometric::Histogram,
+    }
+
+    let registry = prometheus::default_registry();
+    let app_metrics = BucketMetrics::builder().with_registry(registry).build();
+
+    let duration = Duration::from_secs(1);
+    app_metrics.hist().observe(duration.as_secs_f64());
+
+    let encoder = prometheus::TextEncoder::new();
+    let metric_families = registry.gather(); // Wait, need to expose registry
+
+    let mut buffer = vec![];
+    encoder.encode(&metric_families, &mut buffer).unwrap();
+    let output = String::from_utf8(buffer).unwrap();
+
+    assert!(output.contains("test_hist"));
+}
diff --git a/prometric/src/lib.rs b/prometric/src/lib.rs
index c72b3a5..dfd9030 100644
--- a/prometric/src/lib.rs
+++ b/prometric/src/lib.rs
@@ -245,15 +245,15 @@ impl Clone for Histogram {
 }
 
 impl Histogram {
-    pub fn new<B: Into<Vec<f64>>>(
+    pub fn new(
         registry: &prometheus::Registry,
         name: &str,
         help: &str,
         labels: &[&str],
         const_labels: HashMap<String, String>,
-        buckets: Option<B>,
+        buckets: Option<Vec<f64>>,
     ) -> Self {
-        let buckets = buckets.map(Into::into).unwrap_or(prometheus::DEFAULT_BUCKETS.to_vec());
+        let buckets = buckets.unwrap_or(prometheus::DEFAULT_BUCKETS.to_vec());
         let opts =
             prometheus::HistogramOpts::new(name, help).const_labels(const_labels).buckets(buckets);
         let metric = prometheus::HistogramVec::new(opts, labels).unwrap();