diff --git a/e2e/assets/custom_canister/dfx.json b/e2e/assets/custom_canister/dfx.json
index 66454e0324..b6f89010f6 100644
--- a/e2e/assets/custom_canister/dfx.json
+++ b/e2e/assets/custom_canister/dfx.json
@@ -12,6 +12,11 @@
       "candid": "main.did",
       "wasm": "main.wasm",
       "build": "build.sh"
+    },
+    "custom3": {
+      "type": "custom",
+      "candid": "main.did",
+      "wasm": "main.wasm"
     }
   },
   "defaults": {
diff --git a/src/dfx/src/config/dfinity.rs b/src/dfx/src/config/dfinity.rs
index 38e0e4eefb..226125b55c 100644
--- a/src/dfx/src/config/dfinity.rs
+++ b/src/dfx/src/config/dfinity.rs
@@ -776,7 +776,7 @@ impl<'de> Visitor<'de> for PropertiesVisitor {
                 source: source.ok_or_else(|| missing_field("source"))?,
             },
             Some("custom") => CanisterTypeProperties::Custom {
-                build: build.ok_or_else(|| missing_field("build"))?,
+                build: build.unwrap_or_default(),
                 candid: candid.ok_or_else(|| missing_field("candid"))?,
                 wasm: wasm.ok_or_else(|| missing_field("wasm"))?,
             },