diff --git a/src/build.ts b/src/build.ts
index 1bd06617..332de177 100644
--- a/src/build.ts
+++ b/src/build.ts
@@ -57,21 +57,33 @@ function logDiags(diagnostics: Diagnostics[], logger: ILoggingStore) {
   });
 }
 
-export async function extractCandidFromWasm(
-  wasm: Uint8Array
-): Promise<ArrayBuffer> {
-  const mod = await WebAssembly.compile(wasm);
-  let section = WebAssembly.Module.customSections(
-    mod,
-    "icp:public candid:args"
-  );
+function get_wasm_metadata(
+  wasm: WebAssembly.Module,
+  name: string
+): string | undefined {
+  let section = WebAssembly.Module.customSections(wasm, `icp:public ${name}`);
   if (section.length === 0) {
-    section = WebAssembly.Module.customSections(mod, "icp:private candid:args");
+    section = WebAssembly.Module.customSections(wasm, `icp:private ${name}`);
   }
   if (section.length === 0) {
-    throw new Error("Cannot find candid:args metadata in Wasm module");
+    return undefined;
+  }
+  const decoder = new TextDecoder();
+  const bytes = new Uint8Array(section[0]);
+  const str = decoder.decode(bytes);
+  return str;
+}
+
+export async function extractCandidFromWasm(
+  wasm: Uint8Array
+): Promise<[string, undefined | string]> {
+  const mod = await WebAssembly.compile(wasm);
+  const serv = get_wasm_metadata(mod, "candid:service");
+  if (!serv) {
+    throw new Error("Cannot find candid:service metadata in Wasm module");
   }
-  return section;
+  const init = get_wasm_metadata(mod, "candid:args");
+  return [serv, init];
 }
 
 export async function compileCandid(
diff --git a/src/components/CanisterModal.tsx b/src/components/CanisterModal.tsx
index aa8bce21..bdd6bce9 100644
--- a/src/components/CanisterModal.tsx
+++ b/src/components/CanisterModal.tsx
@@ -101,6 +101,7 @@ export function CanisterModal({ isOpen, close, deploySetter }) {
 
   async function deployWasm() {
     if (!candid || !wasm) return;
+    setError("");
     const candidJS = await didToJs(candid);
     const init = candidJS.init({ IDL });
     await close();
@@ -157,8 +158,17 @@ export function CanisterModal({ isOpen, close, deploySetter }) {
       const wasm = new Uint8Array(reader.result);
       setWasm(wasm);
       try {
-        const init = await extractCandidFromWasm(wasm);
-        console.log(init);
+        const [serv, init] = await extractCandidFromWasm(wasm);
+        if (init) {
+          const candid = (await didjs.merge_init_args(serv, init))[0];
+          if (!candid) {
+            setError("Cannot merge candid:args with candid:service from Wasm");
+            return;
+          }
+          setCandid(candid);
+        } else {
+          setCandid(serv);
+        }
       } catch (e) {
         setError(e.toString());
       }
@@ -238,12 +248,14 @@ export function CanisterModal({ isOpen, close, deploySetter }) {
                 accept=".wasm"
                 onChange={handleWasmUpload}
               />
-              <Field
-                type="file"
-                labelText="Upload did file"
-                accept=".did"
-                onChange={handleDidUpload}
-              />
+              {error && (
+                <Field
+                  type="file"
+                  labelText="Upload did file"
+                  accept=".did"
+                  onChange={handleDidUpload}
+                />
+              )}
               {error && <Error>{error}</Error>}
               <ButtonContainer>
                 <MyButton variant="primary" onClick={deployWasm}>
diff --git a/src/didjs.did.js b/src/didjs.did.js
index d4ead032..36d430ce 100644
--- a/src/didjs.did.js
+++ b/src/didjs.did.js
@@ -7,6 +7,11 @@ export const idlFactory = ({ IDL }) => {
       [IDL.Variant({ Ok: IDL.Null, Err: IDL.Text })],
       ["query"]
     ),
+    merge_init_args: IDL.Func(
+      [IDL.Text, IDL.Text],
+      [IDL.Opt(IDL.Text)],
+      ["query"]
+    ),
   });
 };
 export const init = ({ IDL }) => {