diff --git a/carbonmark-api/package.json b/carbonmark-api/package.json
index a4dd439606..ffb55f0079 100644
--- a/carbonmark-api/package.json
+++ b/carbonmark-api/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@klimadao/carbonmark-api",
-  "version": "6.1.0",
+  "version": "6.1.1",
   "description": "An API for exploring Carbonmark project data, prices and activity.",
   "main": "app.ts",
   "scripts": {
diff --git a/carbonmark-api/src/app.constants.ts b/carbonmark-api/src/app.constants.ts
index 820d6ff423..32aa849d7e 100644
--- a/carbonmark-api/src/app.constants.ts
+++ b/carbonmark-api/src/app.constants.ts
@@ -67,6 +67,15 @@ export const RPC_URLS = {
   polygonTestnetRpc: "https://rpc-mumbai.maticvigil.com",
 };
 
+export type RegistryKey = keyof typeof REGISTRIES;
+
+export type RegistryId = (typeof REGISTRIES)[keyof typeof REGISTRIES]["id"];
+
+export const IS_REGISTRY_ID = (id: string): id is RegistryId => {
+  const REGISTRY_IDS = Object.values(REGISTRIES).map((r) => r.id);
+  return REGISTRY_IDS.includes(id);
+};
+
 /** Definitions of available registries */
 export const REGISTRIES = {
   Verra: {
@@ -74,16 +83,19 @@ export const REGISTRIES = {
     title: "Verra",
     url: "https://registry.verra.org",
     api: "https://registry.verra.org/uiapi",
+    decimals: 18,
   },
   GoldStandard: {
     id: "GS",
     title: "Gold Standard",
     url: "https://registry.goldstandard.org",
+    decimals: 18,
   },
   ICR: {
     id: "ICR",
     title: "International Carbon Registry",
     url: "https://www.carbonregistry.com",
+    decimals: 0,
   },
 };
 
diff --git a/carbonmark-api/src/routes/purchases/get.utils.ts b/carbonmark-api/src/routes/purchases/get.utils.ts
index 1751759817..d666a0a6ec 100644
--- a/carbonmark-api/src/routes/purchases/get.utils.ts
+++ b/carbonmark-api/src/routes/purchases/get.utils.ts
@@ -1,5 +1,7 @@
 import { utils } from "ethers";
 import { GetPurchaseByIdQuery } from "src/.generated/types/marketplace.types";
+import { IS_REGISTRY_ID } from "../../../src/app.constants";
+import { formatAmountByRegistry } from "../../../src/utils/marketplace.utils";
 import { Purchase } from "../../models/Purchase.model";
 import { CreditId } from "../../utils/CreditId";
 
@@ -14,12 +16,15 @@ export const composePurchaseModel = (
 ): Purchase => {
   const project = purchase.listing.project;
   // The digits after the registry identifier. e.g 1234 in VCS-1234
-  const [, registryProjectId] = CreditId.splitProjectId(project.key);
+  const [registry, registryProjectId] = CreditId.splitProjectId(project.key);
+
+  if (!IS_REGISTRY_ID(registry)) {
+    throw new Error(`Invalid registry id in composePurchaseModel: ${registry}`);
+  }
+
   return {
     id: purchase.id,
-    amount: purchase.listing.project.key.startsWith("ICR")
-      ? purchase.amount
-      : utils.formatUnits(purchase.amount, 18),
+    amount: formatAmountByRegistry(registry, purchase.amount),
     price: utils.formatUnits(purchase.price, 6),
     listing: {
       id: purchase.listing.id,
diff --git a/carbonmark-api/src/routes/users/[walletOrHandle]/get.ts b/carbonmark-api/src/routes/users/[walletOrHandle]/get.ts
index 34fa4ffd58..19d579b51e 100644
--- a/carbonmark-api/src/routes/users/[walletOrHandle]/get.ts
+++ b/carbonmark-api/src/routes/users/[walletOrHandle]/get.ts
@@ -1,5 +1,6 @@
 import { utils } from "ethers";
 import { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
+import { IS_REGISTRY_ID } from "../../../../src/app.constants";
 import { Activity } from "../../../models/Activity.model";
 import { User } from "../../../models/User.model";
 import { getActiveListings } from "../../../utils/helpers/listings.utils";
@@ -8,7 +9,10 @@ import {
   getProfileByHandle,
   getUserProfilesByIds,
 } from "../../../utils/helpers/users.utils";
-import { formatListing } from "../../../utils/marketplace.utils";
+import {
+  formatAmountByRegistry,
+  formatListing,
+} from "../../../utils/marketplace.utils";
 import { Params, Querystring, schema } from "./get.schema";
 import {
   getHoldingsByWallet,
@@ -82,15 +86,23 @@ const handler = (fastify: FastifyInstance) =>
             handle:
               UserProfilesMap.get(a.seller.id.toLowerCase())?.handle || null,
           };
+
+          const registry = a.project.key.split("-")[0];
+
+          if (!IS_REGISTRY_ID(registry)) {
+            throw new Error(
+              `Invalid registry id in getUserProfilesByIds: ${registry}`
+            );
+          }
+
           return {
             ...a,
-            amount: a.project.key.startsWith("ICR")
-              ? a.amount
-              : utils.formatUnits(a.amount || "0", 18),
+            amount: formatAmountByRegistry(registry, a.amount || "0"),
             price: utils.formatUnits(a.price || "0", 6),
-            previousAmount: a.project.key.startsWith("ICR")
-              ? a.previousAmount
-              : utils.formatUnits(a.previousAmount || "0", 18),
+            previousAmount: formatAmountByRegistry(
+              registry,
+              a.previousAmount || "0"
+            ),
             previousPrice: utils.formatUnits(a.previousPrice || "0", 6),
             buyer: buyer || null,
             seller: seller || null,
diff --git a/carbonmark-api/src/utils/helpers/activities.utils.ts b/carbonmark-api/src/utils/helpers/activities.utils.ts
index f3bfaaae6a..d3d2479026 100644
--- a/carbonmark-api/src/utils/helpers/activities.utils.ts
+++ b/carbonmark-api/src/utils/helpers/activities.utils.ts
@@ -1,10 +1,12 @@
 import { utils } from "ethers";
 import { FastifyInstance } from "fastify";
 import { set, sortBy } from "lodash";
+import { IS_REGISTRY_ID } from "../../../src/app.constants";
 import { ActivityType } from "../../.generated/types/marketplace.types";
 import { Activity } from "../../models/Activity.model";
 import { CreditId } from "../CreditId";
 import { GQL_SDK } from "../gqlSdk";
+import { formatAmountByRegistry } from "../marketplace.utils";
 import { getUserProfilesByIds } from "./users.utils";
 
 type ActivitiesParams = {
@@ -17,23 +19,28 @@ const mapUserToActivities = async (
   activities: Activity[],
   fastify: FastifyInstance
 ): Promise<Activity[]> => {
-  const formattedActivities = activities.map((activity) => ({
-    ...activity,
-    price: activity.price ? utils.formatUnits(activity.price, 6) : null,
-    previousPrice: activity.previousPrice
-      ? utils.formatUnits(activity.previousPrice, 6)
-      : null,
-    amount: activity.amount
-      ? activity.project.key.startsWith("ICR")
-        ? activity.amount
-        : utils.formatUnits(activity.amount, 18)
-      : null,
-    previousAmount: activity.previousAmount
-      ? activity.project.key.startsWith("ICR")
-        ? activity.amount
-        : utils.formatUnits(activity.previousAmount, 18)
-      : null,
-  }));
+  const formattedActivities = activities.map((activity) => {
+    const registry = activity.project.key.split("-")[0];
+
+    if (!IS_REGISTRY_ID(registry)) {
+      throw new Error(
+        `Invalid registry id in mapUserToActivities: ${registry}`
+      );
+    }
+    return {
+      ...activity,
+      price: activity.price ? utils.formatUnits(activity.price, 6) : null,
+      previousPrice: activity.previousPrice
+        ? utils.formatUnits(activity.previousPrice, 6)
+        : null,
+      amount: activity.amount
+        ? formatAmountByRegistry(registry, activity.amount)
+        : null,
+      previousAmount: activity.previousAmount
+        ? formatAmountByRegistry(registry, activity.previousAmount)
+        : null,
+    };
+  });
 
   const userIds = new Set<string>();
   formattedActivities.forEach((activity) => {
diff --git a/carbonmark-api/src/utils/marketplace.utils.ts b/carbonmark-api/src/utils/marketplace.utils.ts
index bfb08914a5..d2c338068d 100644
--- a/carbonmark-api/src/utils/marketplace.utils.ts
+++ b/carbonmark-api/src/utils/marketplace.utils.ts
@@ -1,5 +1,11 @@
 import { utils } from "ethers";
+import { formatUnits } from "ethers/lib/utils";
 import { compact } from "lodash/fp";
+import {
+  IS_REGISTRY_ID,
+  REGISTRIES,
+  RegistryId,
+} from "../../src/app.constants";
 import {
   GetProjectsQuery,
   Listing,
@@ -32,27 +38,41 @@ export type GetProjectListing = NonNullable<
   GetProjectsQuery["projects"][number]["listings"]
 >[number];
 
+/** Format amounts or quantities by registry decimals */
+/** Currently all registries use 18 decimals except ICR, which uses 0  */
+
+export const formatAmountByRegistry = (
+  registryId: RegistryId,
+  quantity: string
+) => {
+  const registry = Object.values(REGISTRIES).find((r) => r.id === registryId);
+
+  if (!registry) {
+    throw new Error(`Registry with id ${registryId} not found.`);
+  }
+
+  return formatUnits(quantity, registry.decimals);
+};
+
 /** Formats a gql.marketplace listing to match Listing.model, and formats integers */
 
 export const formatListing = (listing: GetProjectListing): ListingModel => {
   const registry = listing.project.key.split("-")[0];
 
+  if (!IS_REGISTRY_ID(registry)) {
+    throw new Error(`Invalid registry id in formatListing: ${registry}`);
+  }
+
   return {
     ...formatGraphTimestamps(listing),
 
-    leftToSell:
-      registry === "ICR"
-        ? listing.leftToSell
-        : utils.formatUnits(listing.leftToSell, 18),
+    leftToSell: formatAmountByRegistry(registry, listing.leftToSell),
     singleUnitPrice: utils.formatUnits(listing.singleUnitPrice, 6),
-    minFillAmount:
-      registry === "ICR"
-        ? listing.minFillAmount
-        : utils.formatUnits(listing.minFillAmount, 18),
-    totalAmountToSell:
-      registry === "ICR"
-        ? listing.totalAmountToSell
-        : utils.formatUnits(listing.totalAmountToSell, 18),
+    minFillAmount: formatAmountByRegistry(registry, listing.minFillAmount),
+    totalAmountToSell: formatAmountByRegistry(
+      registry,
+      listing.totalAmountToSell
+    ),
     expiration: Number(listing.expiration),
     project: {
       ...listing.project,
diff --git a/carbonmark-api/test/fixtures/marketplace.ts b/carbonmark-api/test/fixtures/marketplace.ts
index 0553ce41b0..7caf426abc 100644
--- a/carbonmark-api/test/fixtures/marketplace.ts
+++ b/carbonmark-api/test/fixtures/marketplace.ts
@@ -15,6 +15,20 @@ const listing = aListing({
   leftToSell: "100000000000000000000",
   updatedAt: "1234",
   createdAt: "1234",
+  project: {
+    id: "VCS-191-2008",
+    key: "VCS-191",
+    vintage: "2008",
+    category: { id: "Renewable Energy" },
+    country: { id: "United States" },
+    methodology: "VM0006",
+    name: "Hydroelectric Fixture",
+    activities: [],
+    listings: [],
+    registry: "VCS",
+    updatedAt: "1234",
+    projectAddress: "0x1234",
+  },
 });
 
 const projectWithListing = aProject({
diff --git a/carbonmark-api/test/routes/projects/[id]/get.test.ts b/carbonmark-api/test/routes/projects/[id]/get.test.ts
index fb0c16408e..e7224362f3 100644
--- a/carbonmark-api/test/routes/projects/[id]/get.test.ts
+++ b/carbonmark-api/test/routes/projects/[id]/get.test.ts
@@ -23,10 +23,6 @@ describe("GET /projects/:id", () => {
     }
   });
 
-  afterEach(async () => {
-    nock.cleanAll();
-  });
-
   test("Returns project from CMS without prices or listings", async () => {
     nock(SANITY_URLS.cms)
       .post("")
@@ -99,10 +95,6 @@ describe("GET /projects/:id", () => {
         },
       });
 
-    nock(GRAPH_URLS["mumbai"].marketplace).post("").reply(200, {
-      data: {},
-    });
-
     const response = await fastify.inject({
       method: "GET",
       url: `${DEV_URL}/projects/VCS-191-2008?network=polygon`,
diff --git a/carbonmark-api/test/routes/projects/get.test.mocks.ts b/carbonmark-api/test/routes/projects/get.test.mocks.ts
index 2338e7f6fb..77d2c56b7c 100644
--- a/carbonmark-api/test/routes/projects/get.test.mocks.ts
+++ b/carbonmark-api/test/routes/projects/get.test.mocks.ts
@@ -152,12 +152,6 @@ export const mockMarketplaceProjects = (override?: Project[]) => {
     .reply(200, {
       data: { projects: override ?? [fixtures.marketplace.projectWithListing] },
     });
-
-  nock(GRAPH_URLS["mumbai"].marketplace)
-    .post("")
-    .reply(200, {
-      data: { projects: [fixtures.marketplace.projectWithListing] },
-    });
 };
 //Mocks all categories, countries and vintages
 export const mockMarketplaceArgs = () => {