diff --git a/keyserver/src/fetchers/upload-fetchers.js b/keyserver/src/fetchers/upload-fetchers.js
--- a/keyserver/src/fetchers/upload-fetchers.js
+++ b/keyserver/src/fetchers/upload-fetchers.js
@@ -114,9 +114,9 @@
   return `${baseDomain}${uploadPath}`;
 }
 
-function makeUploadURI(holder: ?string, id: string, secret: string): string {
-  if (holder) {
-    return makeBlobServiceURI(holder);
+function makeUploadURI(blobHash: ?string, id: string, secret: string): string {
+  if (blobHash) {
+    return makeBlobServiceURI(blobHash);
   }
   return getUploadURL(id, secret);
 }
diff --git a/lib/facts/blob-service.js b/lib/facts/blob-service.js
--- a/lib/facts/blob-service.js
+++ b/lib/facts/blob-service.js
@@ -7,7 +7,7 @@
 
 const httpEndpoints = Object.freeze({
   GET_BLOB: {
-    path: '/blob/:holder',
+    path: '/blob/:blobHash',
     method: 'GET',
   },
   ASSIGN_HOLDER: {
diff --git a/lib/media/media-utils.js b/lib/media/media-utils.js
--- a/lib/media/media-utils.js
+++ b/lib/media/media-utils.js
@@ -10,7 +10,7 @@
 import {
   isBlobServiceURI,
   getBlobFetchableURL,
-  holderFromBlobServiceURI,
+  blobHashFromBlobServiceURI,
 } from '../utils/blob-service.js';
 
 const maxDimensions = Object.freeze({ width: 1920, height: 1920 });
@@ -52,8 +52,8 @@
 
 function fetchableMediaURI(uri: string): string {
   if (isBlobServiceURI(uri)) {
-    const holder = holderFromBlobServiceURI(uri);
-    return getBlobFetchableURL(holder);
+    const blobHash = blobHashFromBlobServiceURI(uri);
+    return getBlobFetchableURL(blobHash);
   }
 
   return uri;
diff --git a/lib/utils/blob-service.js b/lib/utils/blob-service.js
--- a/lib/utils/blob-service.js
+++ b/lib/utils/blob-service.js
@@ -7,24 +7,32 @@
 
 const BLOB_SERVICE_URI_PREFIX = 'comm-blob-service://';
 
-function makeBlobServiceURI(holder: string): string {
-  return `${BLOB_SERVICE_URI_PREFIX}${holder}`;
+function makeBlobServiceURI(blobHash: string): string {
+  return `${BLOB_SERVICE_URI_PREFIX}${blobHash}`;
 }
 
 function isBlobServiceURI(uri: string): boolean {
   return uri.startsWith(BLOB_SERVICE_URI_PREFIX);
 }
 
-function holderFromBlobServiceURI(uri: string): string {
+/**
+ * Returns the base64url-encoded blob hash from a blob service URI.
+ * Throws an error if the URI is not a blob service URI.
+ */
+function blobHashFromBlobServiceURI(uri: string): string {
   invariant(isBlobServiceURI(uri), 'Not a blob service URI');
   return uri.slice(BLOB_SERVICE_URI_PREFIX.length);
 }
 
-function holderFromURI(uri: string): ?string {
+/**
+ * Returns the base64url-encoded blob hash from a blob service URI.
+ * Returns null if the URI is not a blob service URI.
+ */
+function blobHashFromURI(uri: string): ?string {
   if (!isBlobServiceURI(uri)) {
     return null;
   }
-  return holderFromBlobServiceURI(uri);
+  return blobHashFromBlobServiceURI(uri);
 }
 
 function makeBlobServiceEndpointURL(
@@ -38,17 +46,17 @@
   return `${blobServiceConfig.url}${path}`;
 }
 
-function getBlobFetchableURL(holder: string): string {
+function getBlobFetchableURL(blobHash: string): string {
   return makeBlobServiceEndpointURL(blobServiceConfig.httpEndpoints.GET_BLOB, {
-    holder,
+    blobHash,
   });
 }
 
 export {
   makeBlobServiceURI,
   isBlobServiceURI,
-  holderFromURI,
-  holderFromBlobServiceURI,
+  blobHashFromURI,
+  blobHashFromBlobServiceURI,
   getBlobFetchableURL,
   makeBlobServiceEndpointURL,
 };