diff --git a/datafusion/substrait/src/extensions.rs b/datafusion/substrait/src/extensions.rs
index 079292898226..27d6c150304d 100644
--- a/datafusion/substrait/src/extensions.rs
+++ b/datafusion/substrait/src/extensions.rs
@@ -38,7 +38,7 @@ impl Extensions {
     /// Registers a function and returns the anchor (reference) to it. If the function has already
     /// been registered, it returns the existing anchor.
     /// Function names are case-insensitive (converted to lowercase).
-    pub fn register_function(&mut self, function_name: String) -> u32 {
+    pub fn register_function(&mut self, function_name: &str) -> u32 {
         let function_name = function_name.to_lowercase();
 
         // Some functions are named differently in Substrait default extensions than in DF
@@ -64,7 +64,7 @@ impl Extensions {
 
     /// Registers a type and returns the anchor (reference) to it. If the type has already
     /// been registered, it returns the existing anchor.
-    pub fn register_type(&mut self, type_name: String) -> u32 {
+    pub fn register_type(&mut self, type_name: &str) -> u32 {
         let type_name = type_name.to_lowercase();
         match self.types.iter().find(|(_, t)| *t == &type_name) {
             Some((type_anchor, _)) => *type_anchor, // Type has been registered
diff --git a/datafusion/substrait/src/lib.rs b/datafusion/substrait/src/lib.rs
index 8bc31569f294..51e3d8365130 100644
--- a/datafusion/substrait/src/lib.rs
+++ b/datafusion/substrait/src/lib.rs
@@ -23,6 +23,9 @@
 // Make sure fast / cheap clones on Arc are explicit:
 // https://github.com/apache/datafusion/issues/11143
 #![cfg_attr(not(test), deny(clippy::clone_on_ref_ptr))]
+// https://github.com/apache/datafusion/issues/18503
+#![deny(clippy::needless_pass_by_value)]
+#![cfg_attr(test, allow(clippy::needless_pass_by_value))]
 
 //! Serialize / Deserialize DataFusion Plans to [Substrait.io]
 //!
diff --git a/datafusion/substrait/src/logical_plan/consumer/expr/mod.rs b/datafusion/substrait/src/logical_plan/consumer/expr/mod.rs
index 7358f1422f1b..ba892259852a 100644
--- a/datafusion/substrait/src/logical_plan/consumer/expr/mod.rs
+++ b/datafusion/substrait/src/logical_plan/consumer/expr/mod.rs
@@ -221,7 +221,7 @@ mod tests {
         // Just registering a single function (index 0) so that the plan
         // does not throw a "function not found" error.
         let mut extensions = Extensions::default();
-        extensions.register_function("count".to_string());
+        extensions.register_function("count");
         consumer.extensions = &extensions;
 
         match from_substrait_rex(&consumer, &substrait, &DFSchema::empty()).await? {
@@ -248,7 +248,7 @@ mod tests {
         let mut consumer = test_consumer();
 
         let mut extensions = Extensions::default();
-        extensions.register_function("count".to_string());
+        extensions.register_function("count");
         consumer.extensions = &extensions;
 
         match from_substrait_rex(&consumer, &substrait, &DFSchema::empty()).await? {
diff --git a/datafusion/substrait/src/logical_plan/producer/substrait_producer.rs b/datafusion/substrait/src/logical_plan/producer/substrait_producer.rs
index db08e0f7bfd0..54fa9ea5daa4 100644
--- a/datafusion/substrait/src/logical_plan/producer/substrait_producer.rs
+++ b/datafusion/substrait/src/logical_plan/producer/substrait_producer.rs
@@ -67,11 +67,11 @@ use substrait::proto::{
 /// impl SubstraitProducer for CustomSubstraitProducer {
 ///
 ///     fn register_function(&mut self, signature: String) -> u32 {
-///        self.extensions.register_function(signature)
+///        self.extensions.register_function(&signature)
 ///     }
 ///
 ///     fn register_type(&mut self, type_name: String) -> u32 {
-///         self.extensions.register_type(type_name)
+///         self.extensions.register_type(&type_name)
 ///     }
 ///
 ///     fn get_extensions(self) -> Extensions {
@@ -377,11 +377,11 @@ impl<'a> DefaultSubstraitProducer<'a> {
 
 impl SubstraitProducer for DefaultSubstraitProducer<'_> {
     fn register_function(&mut self, fn_name: String) -> u32 {
-        self.extensions.register_function(fn_name)
+        self.extensions.register_function(&fn_name)
     }
 
     fn register_type(&mut self, type_name: String) -> u32 {
-        self.extensions.register_type(type_name)
+        self.extensions.register_type(&type_name)
     }
 
     fn get_extensions(self) -> Extensions {