diff --git a/CHANGELOG.md b/CHANGELOG.md
index 020e59600..12227f83f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,7 +20,9 @@ A breaking change will get clearly marked in this log.
 
 ### Update
 
-- Upgraded `axios` package to version `^0.21.1` from `^0.19.0` [(#608)](https://github.com/stellar/js-stellar-sdk/pull/608)
+- Upgraded `axios` package to version `^0.21.1` from `^0.19.0` to fix security vulnerabilities [(#608)](https://github.com/stellar/js-stellar-sdk/pull/608)
+
+- Upgraded `js-stellar-base` package to version `^4.0.3` from `^4.0.0` to allow accounts with a balance of zero [(#616)](https://github.com/stellar/js-stellar-sdk/pull/616)
 
 ## [v7.0.0](https://github.com/stellar/js-stellar-sdk/compare/v6.2.0...v7.0.0)
 
diff --git a/package.json b/package.json
index 86bd5efaf..4bedff833 100644
--- a/package.json
+++ b/package.json
@@ -137,7 +137,7 @@
     "eventsource": "^1.0.7",
     "lodash": "^4.17.11",
     "randombytes": "^2.1.0",
-    "stellar-base": "^4.0.0",
+    "stellar-base": "^4.0.3",
     "toml": "^2.3.0",
     "tslib": "^1.10.0",
     "urijs": "^1.19.1",
diff --git a/src/utils.ts b/src/utils.ts
index e52faf27c..a31b18056 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -198,6 +198,12 @@ export namespace Utils {
     }
 
     // verify base64
+    if (!operation.value) {
+      throw new InvalidSep10ChallengeError(
+        "The transaction's operation value should not be null",
+      );
+    }
+
     if (Buffer.from(operation.value.toString(), "base64").length !== 48) {
       throw new InvalidSep10ChallengeError(
         "The transaction's operation value should be a 64 bytes base64 random string",
diff --git a/yarn.lock b/yarn.lock
index 396459927..d7360d0fe 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7777,10 +7777,10 @@ static-extend@^0.1.1:
   resolved "https://registry.yarnpkg.com/statuses/-/statuses-1.5.0.tgz#161c7dac177659fd9811f43771fa99381478628c"
   integrity sha1-Fhx9rBd2Wf2YEfQ3cfqZOBR4Yow=
 
-stellar-base@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/stellar-base/-/stellar-base-4.0.0.tgz#5eb314c76a2054b4df8bcec1278b78172b0fe663"
-  integrity sha512-isn7FoecIcr6lr38oT132UkrYPOEsZy/XAkXteClZpuBBK2aZn0qjyyX4WAoA6cQhnJw/lQQwND+qfijRETvyg==
+stellar-base@^4.0.3:
+  version "4.0.3"
+  resolved "https://registry.yarnpkg.com/stellar-base/-/stellar-base-4.0.3.tgz#03a55fd8ebbd32804d94e87f41bdc56af2a6747b"
+  integrity sha512-Tf1Ko86j4CgUtaiTC6H6qPZ97EziXN6SVokH4FGv5+XvBhFg4V+u9ySMlgPjFbHQumplkHiw8JQx1IZRHnrT3A==
   dependencies:
     base32.js "^0.1.0"
     bignumber.js "^4.0.0"