diff --git a/src/core/lib/security/credentials/oauth2/oauth2_credentials.cc b/src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
index 895776c27f0289f38577e8a7193098aad4d10f48..1dadc01fb866a59dc82da65826c5ce0965e06173 100644
--- a/src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
+++ b/src/core/lib/security/credentials/oauth2/oauth2_credentials.cc
@@ -616,7 +616,7 @@ class StsTokenFetcherCredentials
       if (err != GRPC_ERROR_NONE) return cleanup();
       MaybeAddToBody(
           &body_strvec, "actor_token",
-          reinterpret_cast<const char*>(GRPC_SLICE_START_PTR(subject_token)));
+          reinterpret_cast<const char*>(GRPC_SLICE_START_PTR(actor_token)));
       MaybeAddToBody(&body_strvec, "actor_token_type", actor_token_type_.get());
     }
     return cleanup();
diff --git a/test/core/security/credentials_test.cc b/test/core/security/credentials_test.cc
index f488a2f59254d16e6365e8cf2e965835d136e170..099cdd7aa67d303ba63186fa1fe6ee445d6703c6 100644
--- a/test/core/security/credentials_test.cc
+++ b/test/core/security/credentials_test.cc
@@ -115,6 +115,11 @@ static const char test_signed_jwt[] =
     "U0MDcyZTViYTdmZDkwODg2YzcifQ";
 static const char test_signed_jwt_token_type[] =
     "urn:ietf:params:oauth:token-type:id_token";
+static const char test_signed_jwt2[] =
+    "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCIsImtpZCI6ImY0OTRkN2M1YWU2MGRmOTcyNmM5YW"
+    "U2MDcyZTViYTdnZDkwODg5YzcifQ";
+static const char test_signed_jwt_token_type2[] =
+    "urn:ietf:params:oauth:token-type:jwt";
 static const char test_signed_jwt_path_prefix[] = "test_sign_jwt";
 
 static const char test_service_url[] = "https://foo.com/foo.v1";
@@ -859,8 +864,10 @@ static void validate_sts_token_http_request(const grpc_httpcli_request* request,
                     test_signed_jwt) == 0);
   GPR_ASSERT(strcmp(grpc_uri_get_query_arg(url, "subject_token_type"),
                     test_signed_jwt_token_type) == 0);
-  GPR_ASSERT(grpc_uri_get_query_arg(url, "actor_token") == nullptr);
-  GPR_ASSERT(grpc_uri_get_query_arg(url, "actor_token_type") == nullptr);
+  GPR_ASSERT(strcmp(grpc_uri_get_query_arg(url, "actor_token"),
+                    test_signed_jwt2) == 0);
+  GPR_ASSERT(strcmp(grpc_uri_get_query_arg(url, "actor_token_type"),
+                    test_signed_jwt_token_type2) == 0);
   grpc_uri_destroy(url);
   gpr_free(get_url_equivalent);
 
@@ -884,13 +891,13 @@ static int sts_token_httpcli_post_success(const grpc_httpcli_request* request,
   return 1;
 }
 
-static char* write_tmp_jwt_file(void) {
+static char* write_tmp_jwt_file(const char* jwt_contents) {
   char* path;
   FILE* tmp = gpr_tmpfile(test_signed_jwt_path_prefix, &path);
   GPR_ASSERT(path != nullptr);
   GPR_ASSERT(tmp != nullptr);
-  size_t jwt_length = strlen(test_signed_jwt);
-  GPR_ASSERT(fwrite(test_signed_jwt, 1, jwt_length, tmp) == jwt_length);
+  size_t jwt_length = strlen(jwt_contents);
+  GPR_ASSERT(fwrite(jwt_contents, 1, jwt_length, tmp) == jwt_length);
   fclose(tmp);
   return path;
 }
@@ -901,17 +908,18 @@ static void test_sts_creds_success(void) {
       {"authorization", "Bearer ya29.AHES6ZRN3-HlhAPya30GnW_bHSb_"}};
   grpc_auth_metadata_context auth_md_ctx = {test_service_url, test_method,
                                             nullptr, nullptr};
-  char* test_signed_jwt_path = write_tmp_jwt_file();
+  char* subject_token_path = write_tmp_jwt_file(test_signed_jwt);
+  char* actor_token_path = write_tmp_jwt_file(test_signed_jwt2);
   grpc_sts_credentials_options valid_options = {
       test_sts_endpoint_url,       // sts_endpoint_url
       "resource",                  // resource
       "audience",                  // audience
       "scope",                     // scope
       "requested_token_type",      // requested_token_type
-      test_signed_jwt_path,        // subject_token_path
+      subject_token_path,          // subject_token_path
       test_signed_jwt_token_type,  // subject_token_type
-      nullptr,                     // actor_token_path
-      nullptr                      // actor_token_type
+      actor_token_path,            // actor_token_path
+      test_signed_jwt_token_type2  // actor_token_type
   };
   grpc_call_credentials* creds =
       grpc_sts_credentials_create(&valid_options, nullptr);
@@ -934,7 +942,8 @@ static void test_sts_creds_success(void) {
 
   creds->Unref();
   grpc_httpcli_set_override(nullptr, nullptr);
-  gpr_free(test_signed_jwt_path);
+  gpr_free(subject_token_path);
+  gpr_free(actor_token_path);
 }
 
 static void test_sts_creds_load_token_failure(void) {
@@ -945,7 +954,7 @@ static void test_sts_creds_load_token_failure(void) {
       nullptr, 0);
   grpc_auth_metadata_context auth_md_ctx = {test_service_url, test_method,
                                             nullptr, nullptr};
-  char* test_signed_jwt_path = write_tmp_jwt_file();
+  char* test_signed_jwt_path = write_tmp_jwt_file(test_signed_jwt);
   grpc_sts_credentials_options options = {
       test_sts_endpoint_url,       // sts_endpoint_url
       "resource",                  // resource
@@ -974,7 +983,7 @@ static void test_sts_creds_http_failure(void) {
       nullptr, 0);
   grpc_auth_metadata_context auth_md_ctx = {test_service_url, test_method,
                                             nullptr, nullptr};
-  char* test_signed_jwt_path = write_tmp_jwt_file();
+  char* test_signed_jwt_path = write_tmp_jwt_file(test_signed_jwt);
   grpc_sts_credentials_options valid_options = {
       test_sts_endpoint_url,       // sts_endpoint_url
       "resource",                  // resource