diff --git a/RELEASES.md b/RELEASES.md
index 422a5ef5..d377aa7c 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -13,6 +13,7 @@ Enhancements
 ------------
 
 * Source information is provided when there is an error within a call to a function defined in another module.
+* Source information is provided to the `NativeCallContext` for native Rust functions.
 
 
 Version 0.19.9
diff --git a/src/engine.rs b/src/engine.rs
index 00bce1c7..0eb1fc49 100644
--- a/src/engine.rs
+++ b/src/engine.rs
@@ -126,11 +126,14 @@ impl Imports {
     }
     /// Get specified function via its hash key.
     #[inline(always)]
-    pub fn get_fn(&self, hash: NonZeroU64) -> Option<&CallableFunction> {
+    pub fn get_fn(
+        &self,
+        hash: NonZeroU64,
+    ) -> Option<(&CallableFunction, &Option<ImmutableString>)> {
         self.0
             .iter()
             .rev()
-            .find_map(|(_, m)| m.get_qualified_fn(hash))
+            .find_map(|(_, m)| m.get_qualified_fn(hash).map(|f| (f, m.id_raw())))
     }
     /// Does the specified [`TypeId`][std::any::TypeId] iterator exist in this stack of imported [modules][Module]?
     #[allow(dead_code)]
@@ -2046,15 +2049,16 @@ impl Engine {
                     match self
                         .global_namespace
                         .get_fn(hash_fn, false)
+                        .map(|f| (f, None))
                         .or_else(|| {
-                            self.global_modules
-                                .iter()
-                                .find_map(|m| m.get_fn(hash_fn, false))
+                            self.global_modules.iter().find_map(|m| {
+                                m.get_fn(hash_fn, false).map(|f| (f, m.id_raw().as_ref()))
+                            })
                         })
-                        .or_else(|| mods.get_fn(hash_fn))
+                        .or_else(|| mods.get_fn(hash_fn).map(|(f, source)| (f, source.as_ref())))
                     {
                         // op= function registered as method
-                        Some(func) if func.is_method() => {
+                        Some((func, source)) if func.is_method() => {
                             let mut lock_guard;
                             let lhs_ptr_inner;
 
@@ -2068,14 +2072,16 @@ impl Engine {
                             let args = &mut [lhs_ptr_inner, &mut rhs_val];
 
                             // Overriding exact implementation
+                            let source = if source.is_none() {
+                                state.source.as_ref()
+                            } else {
+                                source
+                            };
                             if func.is_plugin_fn() {
                                 func.get_plugin_fn()
-                                    .call((self, &state.source, &*mods, lib).into(), args)?;
+                                    .call((self, source, &*mods, lib).into(), args)?;
                             } else {
-                                func.get_native_fn()(
-                                    (self, &state.source, &*mods, lib).into(),
-                                    args,
-                                )?;
+                                func.get_native_fn()((self, source, &*mods, lib).into(), args)?;
                             }
                         }
                         // Built-in op-assignment function
diff --git a/src/fn_call.rs b/src/fn_call.rs
index 85da3fcb..38c0dc89 100644
--- a/src/fn_call.rs
+++ b/src/fn_call.rs
@@ -176,15 +176,14 @@ impl Engine {
         self.inc_operations(state, pos)?;
 
         // Check if function access already in the cache
-        if !state.functions_cache.contains_key(&hash_fn) {
+        let func = &*state.functions_cache.entry(hash_fn).or_insert_with(|| {
             // Search for the native function
             // First search registered functions (can override packages)
             // Then search packages
             // Finally search modules
 
             //lib.get_fn(hash_fn, pub_only)
-            let f = self
-                .global_namespace
+            self.global_namespace
                 .get_fn(hash_fn, pub_only)
                 .cloned()
                 .map(|f| (f, None))
@@ -195,13 +194,11 @@ impl Engine {
                             .map(|f| (f, m.id_raw().clone()))
                     })
                 })
-                .or_else(|| mods.get_fn(hash_fn).cloned().map(|f| (f, None)));
-
-            // Store into cache
-            state.functions_cache.insert(hash_fn, f);
-        }
-
-        let func = state.functions_cache.get(&hash_fn).unwrap();
+                .or_else(|| {
+                    mods.get_fn(hash_fn)
+                        .map(|(f, source)| (f.clone(), source.clone()))
+                })
+        });
 
         if let Some((func, source)) = func {
             assert!(func.is_native());
@@ -212,9 +209,9 @@ impl Engine {
 
             // Run external function
             let source = if source.is_none() {
-                &state.source
+                state.source.as_ref()
             } else {
-                source
+                source.as_ref()
             };
             let result = if func.is_plugin_fn() {
                 func.get_plugin_fn()
@@ -1240,10 +1237,10 @@ impl Engine {
 
                 result
             }
-            Some(f) if f.is_plugin_fn() => f
-                .get_plugin_fn()
-                .clone()
-                .call((self, module.id_raw(), &*mods, lib).into(), args.as_mut()),
+            Some(f) if f.is_plugin_fn() => f.get_plugin_fn().clone().call(
+                (self, module.id_raw().as_ref(), &*mods, lib).into(),
+                args.as_mut(),
+            ),
             Some(f) if f.is_native() => {
                 if !f.is_method() {
                     // Clone first argument
@@ -1254,7 +1251,10 @@ impl Engine {
                     }
                 }
 
-                f.get_native_fn()((self, module.id_raw(), &*mods, lib).into(), args.as_mut())
+                f.get_native_fn()(
+                    (self, module.id_raw().as_ref(), &*mods, lib).into(),
+                    args.as_mut(),
+                )
             }
             Some(f) => unreachable!("unknown function type: {:?}", f),
             None if def_val.is_some() => Ok(def_val.unwrap().clone()),
diff --git a/src/fn_native.rs b/src/fn_native.rs
index 261a3935..6144ac5e 100644
--- a/src/fn_native.rs
+++ b/src/fn_native.rs
@@ -63,14 +63,14 @@ pub struct NativeCallContext<'e, 's, 'a, 'm, 'pm: 'm> {
 }
 
 impl<'e, 's, 'a, 'm, 'pm: 'm, M: AsRef<[&'pm Module]> + ?Sized>
-    From<(&'e Engine, &'s Option<ImmutableString>, &'a Imports, &'m M)>
+    From<(&'e Engine, Option<&'s ImmutableString>, &'a Imports, &'m M)>
     for NativeCallContext<'e, 's, 'a, 'm, 'pm>
 {
     #[inline(always)]
-    fn from(value: (&'e Engine, &'s Option<ImmutableString>, &'a Imports, &'m M)) -> Self {
+    fn from(value: (&'e Engine, Option<&'s ImmutableString>, &'a Imports, &'m M)) -> Self {
         Self {
             engine: value.0,
-            source: value.1.as_ref().map(|s| s.as_str()),
+            source: value.1.map(|s| s.as_str()),
             mods: Some(value.2),
             lib: value.3.as_ref(),
         }