diff --git a/src/param/boolean.rs b/src/param/boolean.rs
index 9ab1863e..18ed1c7b 100644
--- a/src/param/boolean.rs
+++ b/src/param/boolean.rs
@@ -12,24 +12,24 @@ pub struct BoolParam {
     /// The field's current value. Should be initialized with the default value.
     pub value: bool,
     /// The field's default value.
-    pub default: bool,
+    default: bool,
 
     /// Flags to control the parameter's behavior. See [`ParamFlags`].
-    pub flags: ParamFlags,
+    flags: ParamFlags,
     /// Optional callback for listening to value changes. The argument passed to this function is
     /// the parameter's new value. This should not do anything expensive as it may be called
     /// multiple times in rapid succession, and it can be run from both the GUI and the audio
     /// thread.
-    pub value_changed: Option<Arc<dyn Fn(bool) + Send + Sync>>,
+    value_changed: Option<Arc<dyn Fn(bool) + Send + Sync>>,
 
     /// The parameter's human readable display name.
-    pub name: String,
+    name: String,
     /// Optional custom conversion function from a boolean value to a string.
-    pub value_to_string: Option<Arc<dyn Fn(bool) -> String + Send + Sync>>,
+    value_to_string: Option<Arc<dyn Fn(bool) -> String + Send + Sync>>,
     /// Optional custom conversion function from a string to a boolean value. If the string cannot
     /// be parsed, then this should return a `None`. If this happens while the parameter is being
     /// updated then the update will be canceled.
-    pub string_to_value: Option<Arc<dyn Fn(&str) -> Option<bool> + Send + Sync>>,
+    string_to_value: Option<Arc<dyn Fn(&str) -> Option<bool> + Send + Sync>>,
 }
 
 #[allow(clippy::derivable_impls)]
diff --git a/src/param/float.rs b/src/param/float.rs
index 229aa993..bb7e8877 100644
--- a/src/param/float.rs
+++ b/src/param/float.rs
@@ -26,13 +26,13 @@ pub struct FloatParam {
     /// locality, but it does allow for a much nicer declarative API.
     pub value: f32,
     /// The field's default plain, unnormalized value.
-    pub default: f32,
+    default: f32,
     /// An optional smoother that will automatically interpolate between the new automation values
     /// set by the host.
     pub smoothed: Smoother<f32>,
 
     /// Flags to control the parameter's behavior. See [`ParamFlags`].
-    pub flags: ParamFlags,
+    flags: ParamFlags,
     /// Optional callback for listening to value changes. The argument passed to this function is
     /// the parameter's new **plain** value. This should not do anything expensive as it may be
     /// called multiple times in rapid succession.
@@ -41,28 +41,28 @@ pub struct FloatParam {
     /// parameters struct, move a clone of that `Arc` into this closure, and then modify that.
     ///
     /// TODO: We probably also want to pass the old value to this function.
-    pub value_changed: Option<Arc<dyn Fn(f32) + Send + Sync>>,
+    value_changed: Option<Arc<dyn Fn(f32) + Send + Sync>>,
 
     /// The distribution of the parameter's values.
-    pub range: FloatRange,
+    range: FloatRange,
     /// The distance between discrete steps in this parameter. Mostly useful for quantizing GUI
     /// input. If this is set and if [`value_to_string`][Self::value_to_string] is not set, then
     /// this is also used when formatting the parameter. This must be a positive, nonzero number.
-    pub step_size: Option<f32>,
+    step_size: Option<f32>,
     /// The parameter's human readable display name.
-    pub name: String,
+    name: String,
     /// The parameter value's unit, added after [`value_to_string`][Self::value_to_string] if that
     /// is set. NIH-plug will not automatically add a space before the unit.
-    pub unit: &'static str,
+    unit: &'static str,
     /// Optional custom conversion function from a plain **unnormalized** value to a string.
-    pub value_to_string: Option<Arc<dyn Fn(f32) -> String + Send + Sync>>,
+    value_to_string: Option<Arc<dyn Fn(f32) -> String + Send + Sync>>,
     /// Optional custom conversion function from a string to a plain **unnormalized** value. If the
     /// string cannot be parsed, then this should return a `None`. If this happens while the
     /// parameter is being updated then the update will be canceled.
     ///
     /// The input string may or may not contain the unit, so you will need to be able to handle
     /// that.
-    pub string_to_value: Option<Arc<dyn Fn(&str) -> Option<f32> + Send + Sync>>,
+    string_to_value: Option<Arc<dyn Fn(&str) -> Option<f32> + Send + Sync>>,
 }
 
 impl Default for FloatParam {
diff --git a/src/param/integer.rs b/src/param/integer.rs
index 0d1e3a19..aa8d2147 100644
--- a/src/param/integer.rs
+++ b/src/param/integer.rs
@@ -26,13 +26,13 @@ pub struct IntParam {
     /// locality, but it does allow for a much nicer declarative API.
     pub value: i32,
     /// The field's default plain, unnormalized value.
-    pub default: i32,
+    pub(crate) default: i32,
     /// An optional smoother that will automatically interpolate between the new automation values
     /// set by the host.
     pub smoothed: Smoother<i32>,
 
     /// Flags to control the parameter's behavior. See [`ParamFlags`].
-    pub flags: ParamFlags,
+    pub(crate) flags: ParamFlags,
     /// Optional callback for listening to value changes. The argument passed to this function is
     /// the parameter's new **plain** value. This should not do anything expensive as it may be
     /// called multiple times in rapid succession.
@@ -41,24 +41,24 @@ pub struct IntParam {
     /// parameters struct, move a clone of that `Arc` into this closure, and then modify that.
     ///
     /// TODO: We probably also want to pass the old value to this function.
-    pub value_changed: Option<Arc<dyn Fn(i32) + Send + Sync>>,
+    pub(crate) value_changed: Option<Arc<dyn Fn(i32) + Send + Sync>>,
 
     /// The distribution of the parameter's values.
-    pub range: IntRange,
+    pub(crate) range: IntRange,
     /// The parameter's human readable display name.
-    pub name: String,
+    pub(crate) name: String,
     /// The parameter value's unit, added after `value_to_string` if that is set. NIH-plug will not
     /// automatically add a space before the unit.
-    pub unit: &'static str,
+    pub(crate) unit: &'static str,
     /// Optional custom conversion function from a plain **unnormalized** value to a string.
-    pub value_to_string: Option<Arc<dyn Fn(i32) -> String + Send + Sync>>,
+    pub(crate) value_to_string: Option<Arc<dyn Fn(i32) -> String + Send + Sync>>,
     /// Optional custom conversion function from a string to a plain **unnormalized** value. If the
     /// string cannot be parsed, then this should return a `None`. If this happens while the
     /// parameter is being updated then the update will be canceled.
     ///
     /// The input string may or may not contain the unit, so you will need to be able to handle
     /// that.
-    pub string_to_value: Option<Arc<dyn Fn(&str) -> Option<i32> + Send + Sync>>,
+    pub(crate) string_to_value: Option<Arc<dyn Fn(&str) -> Option<i32> + Send + Sync>>,
 }
 
 impl Default for IntParam {