diff --git a/bindings/rust/src/lib.rs b/bindings/rust/src/lib.rs
index 66465ae5c..3629ec8e5 100644
--- a/bindings/rust/src/lib.rs
+++ b/bindings/rust/src/lib.rs
@@ -191,16 +191,70 @@ impl Drop for Instance {
     }
 }
 
+struct HostFunction {
+    module: CString,
+    name: CString,
+    inputs: Vec<sys::FizzyValueType>,
+    output: sys::FizzyValueType,
+    index: usize,
+}
+
+unsafe extern "C" fn host_callback(
+    host_context: *mut std::os::raw::c_void,
+    instance: *mut sys::FizzyInstance,
+    args: *const sys::FizzyValue,
+    context: *mut sys::FizzyExecutionContext,
+) -> sys::FizzyExecutionResult {
+    println!("host fuction called!");
+    //unimplemented!()
+    sys::FizzyExecutionResult {
+        trapped: false,
+        has_value: false,
+        value: sys::FizzyValue { i32: 0 },
+    }
+}
+
+fn create_function_import_list(
+    host_functions: &[&HostFunction],
+) -> Vec<sys::FizzyImportedFunction> {
+    assert!(host_functions.len() == 1);
+    let host_function = &host_functions[0];
+    let fn_type = sys::FizzyFunctionType {
+        output: host_function.output,
+        inputs: host_function.inputs.as_ptr(),
+        inputs_size: host_function.inputs.len(),
+    };
+    let ext_fn = sys::FizzyExternalFunction {
+        type_: fn_type,
+        function: Some(host_callback),
+        context: std::ptr::null_mut(),
+    };
+    vec![sys::FizzyImportedFunction {
+        module: host_function.module.as_ptr(),
+        name: host_function.name.as_ptr(),
+        external_function: ext_fn,
+    }]
+}
+
 impl Module {
     /// Create an instance of a module.
     // TODO: support imported functions
     pub fn instantiate(self) -> Result<Instance, Error> {
         let mut err = FizzyErrorBox::new();
+        let host_fn1 = HostFunction {
+            module: CString::new("env").expect("cstring to work"),
+            name: CString::new("print").expect("cstring to work"),
+            inputs: vec![],
+            output: sys::FizzyValueTypeVoid,
+            index: 0,
+        };
+        let import_list = vec![&host_fn1];
+        let import_list = create_function_import_list(&import_list);
         let ptr = unsafe {
-            sys::fizzy_instantiate(
+            sys::fizzy_resolve_instantiate(
                 self.0.as_ptr(),
-                std::ptr::null(),
-                0,
+                import_list.as_ptr(),
+                import_list.len(),
                 std::ptr::null(),
                 std::ptr::null(),
                 std::ptr::null(),
@@ -1271,9 +1325,7 @@ mod tests {
         assert!(instance.is_err());
         assert_eq!(
             instance.err().unwrap(),
-            Error::InstantiationFailed(
-                "module requires 1 imported functions, 0 provided".to_string()
-            )
+            Error::InstantiationFailed("imported function env.adler32 is required".to_string())
         );
     }
 
@@ -1298,4 +1350,29 @@ mod tests {
         assert!(result.is_err());
         assert_eq!(result.err().unwrap(), Error::Trapped);
     }
+
+    #[test]
+    fn execute_host_function2() {
+        /* wat2wasm
+        (module
+          (func $print (import "env" "print"))
+          (func (export "foo")
+            call $print
+          )
+        )
+        */
+        let input = hex::decode(
+        "0061736d01000000010401600000020d0103656e76057072696e7400000302010007070103666f6f00010a0601040010000b").unwrap();
+
+        let module = parse(&input);
+        assert!(module.is_ok());
+        let instance = module.unwrap().instantiate();
+        assert!(instance.is_ok());
+        let mut instance = instance.unwrap();
+
+        // Successful execution.
+        let result = instance.execute("foo", &[]);
+        assert!(result.is_ok());
+        assert!(result.unwrap().is_none());
+    }
 }
diff --git a/lib/fizzy/capi.cpp b/lib/fizzy/capi.cpp
index 9aa7f60d1..30ed1467f 100644
--- a/lib/fizzy/capi.cpp
+++ b/lib/fizzy/capi.cpp
@@ -10,6 +10,7 @@
 #include <fizzy/fizzy.h>
 #include <cstring>
 #include <memory>
+#include <iostream>
 
 namespace
 {
@@ -275,6 +276,7 @@ inline fizzy::ImportedFunction unwrap(const FizzyImportedFunction& c_imported_fu
 
     auto function = unwrap(
         c_imported_func.external_function.function, c_imported_func.external_function.context);
+    std::cout << "c_imported_func:" << c_imported_func.module << ":" << c_imported_func.name << std::endl;
 
     return {c_imported_func.module, c_imported_func.name, std::move(inputs), output,
         std::move(function)};
@@ -641,6 +643,11 @@ FizzyInstance* fizzy_instantiate(const FizzyModule* module,
         set_success(error);
         return wrap(instance.release());
     }
+    catch (fizzy::instantiate_error const& e)
+    {
+        std::cout << e.what() << std::endl;
+        return nullptr;
+    }
     catch (...)
     {
         set_error_from_current_exception(error);
diff --git a/lib/fizzy/instantiate.cpp b/lib/fizzy/instantiate.cpp
index c919a1a1c..8b889a087 100644
--- a/lib/fizzy/instantiate.cpp
+++ b/lib/fizzy/instantiate.cpp
@@ -7,6 +7,7 @@
 #include <algorithm>
 #include <cassert>
 #include <cstring>
+#include <iostream>
 
 namespace fizzy
 {
@@ -261,7 +262,7 @@ ExternalFunction find_imported_function(const std::string& module, const std::st
     const FuncType& module_func_type, const std::vector<ImportedFunction>& imported_functions)
 {
     const auto it = std::find_if(imported_functions.begin(), imported_functions.end(),
-        [module, name](const auto& func) { return module == func.module && name == func.name; });
+        [module, name](const auto& func) { std::cout << func.module << ":" << func.name << std::endl; return module == func.module && name == func.name; });
 
     if (it == imported_functions.end())
     {