diff --git a/gitrise.sh b/gitrise.sh
index af21d11..9c6dd0b 100755
--- a/gitrise.sh
+++ b/gitrise.sh
@@ -12,7 +12,7 @@ build_slug=""
 build_url=""
 build_status=0
 current_build_status_text=""
-exit_code=""
+exit_code=0
 log_url=""
 build_artifacts_slugs=()
 
@@ -224,7 +224,7 @@ function process_build() {
         if [[ $TESTING_ENABLED == true ]] && [[ "${FUNCNAME[1]}" != "testFailureUponReceivingHTMLREsponse" ]]; then break; fi
         sleep "$STATUS_POLLING_INTERVAL"
     done
-    if [ "$build_status" = 1 ]; then exit_code=0; else exit_code=1; fi
+    if [ "$build_status" != 1 ]; then exit_code=$(( exit_code + 1 )); fi
 } 
 
 function check_build_status() {
@@ -406,7 +406,7 @@ function download_single_artifact() {
     artifact_title=$(echo "$response" | jq ".data.title" | sed 's/"//g')
     printf "%b" "Downloading build artifact $artifact_title\n"
     curl -X GET "$artifact_url" --output "./build_artifacts/$artifact_title"
-    exit_code=$?
+    exit_code=$(( exit_code + $? ))
 }
 
 function download_build_artifacts() {
@@ -437,4 +437,4 @@ if [ "$0" = "${BASH_SOURCE[0]}" ] && [ -z "${TESTING_ENABLED}" ]; then
     build_status_message "$build_status"
     [ -n "$BUILD_ARTIFACTS" ] && download_build_artifacts
     exit ${exit_code}
-fi
\ No newline at end of file
+fi
diff --git a/tests/download_single_artifacts_tests.sh b/tests/download_single_artifacts_tests.sh
new file mode 100755
index 0000000..417f18e
--- /dev/null
+++ b/tests/download_single_artifacts_tests.sh
@@ -0,0 +1,51 @@
+#!/usr/bin/env bash
+
+# shellcheck disable=SC1091,SC2155,SC2154,SC2034
+# Not following: (error message here)
+# Declare and assign separately to avoid masking return values.
+# var is referenced but not assigned.
+# var appears unused
+
+source ./gitrise.sh -T
+
+testExitCodeRemainsZeroWhenSuccessful() {
+    exit_code=0
+    # shellcheck disable=SC2317  # Don't warn about unreachable commands in this function
+    curl() {
+        return 0
+    }
+
+    download_single_artifact "some-slug" &> /dev/null
+    local expected_code=0
+    assertEquals "Status codes did not match" "$expected_code" "${exit_code}"
+}
+
+testDoesNotOverrideExistingExitCode() {
+    exit_code=1
+    # shellcheck disable=SC2317  # Don't warn about unreachable commands in this function
+    curl() {
+        return 0
+    }
+
+    download_single_artifact "some-slug" &> /dev/null
+    local expected_code=1
+    assertEquals "Status codes did not match" "$expected_code" "${exit_code}"
+}
+
+testAccumulatesErrorsOnCurlFailures() {
+    exit_code=1
+    # shellcheck disable=SC2317  # Don't warn about unreachable commands in this function
+    curl() {
+        return 1
+    }
+
+    download_single_artifact "some-slug" &> /dev/null
+    local expected_code=2
+    assertEquals "Status codes did not match" "$expected_code" "${exit_code}"
+}
+
+tearDown() {
+  build_status=0
+}
+
+. ./tests/shunit2