diff --git a/packages/xod-project/src/flatten.js b/packages/xod-project/src/flatten.js
index 0ed3ee3d2..b894ddc44 100644
--- a/packages/xod-project/src/flatten.js
+++ b/packages/xod-project/src/flatten.js
@@ -654,6 +654,9 @@ const traverseUpAndCollectTerminalChain = R.curry(
         R.compose(R.equals(nextNodeId), Link.getLinkInputNodeId),
         links
       );
+      // If the uppermost node has no input link — return collected data
+      if (!nextLink) return collected;
+
       return R.compose(
         traverseUpAndCollectTerminalChain(terminalNodeIds, links),
         R.over(R.lensIndex(0), R.append(nextNodeId)),
diff --git a/packages/xod-project/test/fixtures/cast-custom-types.xodball b/packages/xod-project/test/fixtures/cast-custom-types.xodball
index 95d8320cb..5a6ead60b 100644
--- a/packages/xod-project/test/fixtures/cast-custom-types.xodball
+++ b/packages/xod-project/test/fixtures/cast-custom-types.xodball
@@ -554,6 +554,117 @@
           "type": "xod/patch-nodes/input-byte"
         }
       }
+    },
+    "@/test-wrapped-i2c": {
+      "nodes": {
+        "wrapped-i2c-node": {
+          "id": "wrapped-i2c-node",
+          "position": {
+            "x": -2,
+            "y": -1,
+            "units": "slots"
+          },
+          "type": "@/wrapped-i2c"
+        }
+      },
+      "path": "@/main"
+    },
+    "@/wrapped-i2c": {
+      "links": {
+        "terminal-to-node": {
+          "id": "terminal-to-node",
+          "input": {
+            "nodeId": "test-node",
+            "pinKey": "input-i2c"
+          },
+          "output": {
+            "nodeId": "input-i2c-terminal",
+            "pinKey": "__out__"
+          }
+        }
+      },
+      "nodes": {
+        "test-node": {
+          "id": "test-node",
+          "position": {
+            "x": 1,
+            "y": 1,
+            "units": "slots"
+          },
+          "type": "xod/i2c/test"
+        },
+        "input-i2c-terminal": {
+          "id": "input-i2c-terminal",
+          "label": "I2C",
+          "position": {
+            "x": 1,
+            "y": 0,
+            "units": "slots"
+          },
+          "type": "xod/i2c/input-i2c"
+        }
+      },
+      "path": "@/wrapped-i2c"
+    },
+    "xod/i2c/i2c": {
+      "attachments": [
+        {
+          "filename": "patch.cpp",
+          "encoding": "utf-8",
+          "content": "// implementation"
+        }
+      ],
+      "nodes": {
+        "output-self": {
+          "id": "output-self",
+          "position": {
+            "units": "slots",
+            "x": 2,
+            "y": 2
+          },
+          "type": "xod/patch-nodes/output-self"
+        },
+        "niix": {
+          "id": "niix",
+          "position": {
+            "units": "slots",
+            "x": 2,
+            "y": 1
+          },
+          "type": "xod/patch-nodes/not-implemented-in-xod"
+        }
+      },
+      "path": "xod/i2c/i2c"
+    },
+    "xod/i2c/test": {
+      "attachments": [
+        {
+          "filename": "patch.cpp",
+          "encoding": "utf-8",
+          "content": "// implementation"
+        }
+      ],
+      "nodes": {
+        "input-i2c": {
+          "id": "input-i2c",
+          "position": {
+            "units": "slots",
+            "x": 2,
+            "y": 2
+          },
+          "type": "xod/i2c/input-i2c"
+        },
+        "niix": {
+          "id": "niix",
+          "position": {
+            "units": "slots",
+            "x": 2,
+            "y": 1
+          },
+          "type": "xod/patch-nodes/not-implemented-in-xod"
+        }
+      },
+      "path": "xod/i2c/test"
     }
   }
 }
diff --git a/packages/xod-project/test/flatten.spec.js b/packages/xod-project/test/flatten.spec.js
index 66a243c70..e5714911b 100644
--- a/packages/xod-project/test/flatten.spec.js
+++ b/packages/xod-project/test/flatten.spec.js
@@ -1359,6 +1359,25 @@ describe('Flatten', () => {
           'color-nested~nested-again~hsl-node-to-watch-node-pin-input-string'
         ));
 
+      it('should not create a cast node for a custom type if it not needed', () => {
+        const flatProject = flatten(project, '@/test-wrapped-i2c');
+        Helper.expectEitherRight(newProject => {
+          const nodeIds = R.compose(
+            R.map(Node.getNodeId),
+            Patch.listNodes,
+            Project.getPatchByPathUnsafe('@/test-wrapped-i2c')
+          )(newProject);
+
+          const links = R.compose(
+            Patch.listLinks,
+            Project.getPatchByPathUnsafe('@/test-wrapped-i2c')
+          )(newProject);
+
+          assert.sameMembers(['wrapped-i2c-node~test-node'], nodeIds);
+          assert.isEmpty(links);
+        }, flatProject);
+      });
+
       it('should return Either.Left if custom type does not have a cast node', () => {
         const flatProject = flatten(project, '@/test-no-cast-node');
         Helper.expectEitherError(