diff --git a/lib/runtime-core/src/backing.rs b/lib/runtime-core/src/backing.rs
index 2493e9d35..7449403fa 100644
--- a/lib/runtime-core/src/backing.rs
+++ b/lib/runtime-core/src/backing.rs
@@ -591,16 +591,21 @@ fn import_functions(
                             //                      ^^^^^^^^ `vm::FuncCtx` is purposely leaked.
                             //                               It is dropped by the specific `Drop`
                             //                               implementation of `ImportBacking`.
-                            vmctx: NonNull::new(vmctx).expect("`vmctx` must not be null."),
-                            func_env: match ctx {
-                                Context::External(ctx) => {
-                                    NonNull::new(ctx).map(NonNull::cast)
-                                    //                    ^^^^^^^^^^^^^
-                                    //                    `*mut vm::FuncEnv` was casted to
-                                    //                    `*mut vm::Ctx` to fit in
-                                    //                    `Context::External`. Cast it back.
+                            vmctx: NonNull::new(match ctx {
+                                Context::External(vmctx) => vmctx,
+                                Context::ExternalWithEnv(vmctx_, _) => {
+                                    if vmctx_.is_null() {
+                                        vmctx
+                                    } else {
+                                        vmctx_
+                                    }
                                 }
-                                Context::Internal => None,
+                                _ => vmctx,
+                            })
+                            .expect("`vmctx` must not be null."),
+                            func_env: match ctx {
+                                Context::ExternalWithEnv(_, func_env) => Some(func_env),
+                                _ => None,
                             },
                         })))
                         .unwrap(),
diff --git a/lib/runtime-core/src/export.rs b/lib/runtime-core/src/export.rs
index 7960d76e6..88ec07e40 100644
--- a/lib/runtime-core/src/export.rs
+++ b/lib/runtime-core/src/export.rs
@@ -3,11 +3,12 @@ use crate::{
     module::ModuleInner, table::Table, types::FuncSig, vm,
 };
 use indexmap::map::Iter as IndexMapIter;
-use std::sync::Arc;
+use std::{ptr::NonNull, sync::Arc};
 
 #[derive(Debug, Copy, Clone)]
 pub enum Context {
     External(*mut vm::Ctx),
+    ExternalWithEnv(*mut vm::Ctx, NonNull<vm::FuncEnv>),
     Internal,
 }
 
diff --git a/lib/runtime-core/src/instance.rs b/lib/runtime-core/src/instance.rs
index 5cf92a312..53a5681ff 100644
--- a/lib/runtime-core/src/instance.rs
+++ b/lib/runtime-core/src/instance.rs
@@ -413,6 +413,7 @@ impl InstanceInner {
                     ctx: match ctx {
                         Context::Internal => Context::External(self.vmctx),
                         ctx @ Context::External(_) => ctx,
+                        func_ctx @ Context::ExternalWithEnv(_, _) => func_ctx,
                     },
                     signature,
                 }
@@ -463,7 +464,6 @@ impl InstanceInner {
         };
 
         let signature = SigRegistry.lookup_signature_ref(&module.info.signatures[sig_index]);
-        // let signature = &module.info.signatures[sig_index];
 
         (unsafe { FuncPointer::new(func_ptr) }, ctx, signature)
     }
diff --git a/lib/runtime-core/src/typed_func.rs b/lib/runtime-core/src/typed_func.rs
index 8c6a7826d..cce058182 100644
--- a/lib/runtime-core/src/typed_func.rs
+++ b/lib/runtime-core/src/typed_func.rs
@@ -724,11 +724,7 @@ where
     fn to_export(&self) -> Export {
         let func = unsafe { FuncPointer::new(self.func.as_ptr()) };
         let ctx = match self.func_env {
-            Some(func_env) => Context::External(func_env.cast().as_ptr()),
-            //                                           ^^^^^^
-            //                                           `Context::External` expects a `vm::Ctx`.
-            //                                           Casting to `vm::FuncCtx` happens in the
-            //                                           `backing` module.
+            Some(func_env) => Context::ExternalWithEnv(self.vmctx, func_env),
             None => Context::Internal,
         };
         let signature = Arc::new(FuncSig::new(Args::types(), Rets::types()));