diff --git a/includes/database.php b/includes/database.php
index efa7a3e..70ff330 100644
--- a/includes/database.php
+++ b/includes/database.php
@@ -39,7 +39,7 @@ function plugin_evidence_initialize_database() {
 	$data              = [];
 	$data['columns'][] = ['name' => 'id', 'type' => 'int(11)', 'NULL' => false];
 	$data['columns'][] = ['name' => 'organization', 'type' => 'varchar(200)', 'NULL' => false];
-	$data['primary']   = ['id'];
+	$data['primary']   = 'id';
 	$data['type']      = 'InnoDB';
 	$data['comment']   = 'evidence organizations';
 	api_plugin_db_table_create('evidence', 'plugin_evidence_organization', $data);
@@ -65,7 +65,7 @@ function plugin_evidence_initialize_database() {
 	$data['columns'][] = ['name' => 'method', 'type' => 'enum("get", "walk", "info", "table")', 'default' => 'get', 'NULL' => false];
 	$data['columns'][] = ['name' => 'table_items', 'type' => 'varchar(100)', 'default' => null, 'NULL' => true];
 	$data['columns'][] = ['name' => 'mandatory', 'type' => 'enum("yes","no")', 'default' => 'yes', 'NULL' => false];
-	$data['primary']   = ['id'];
+	$data['primary']   = 'id';
 	$data['type']      = 'InnoDB';
 	$data['comment']   = 'evidence specific';
 	api_plugin_db_table_create('evidence', 'plugin_evidence_specific_query', $data);
diff --git a/tests/Unit/EvidenceDatabaseTest.php b/tests/Unit/EvidenceDatabaseTest.php
index 233ce50..b307a90 100644
--- a/tests/Unit/EvidenceDatabaseTest.php
+++ b/tests/Unit/EvidenceDatabaseTest.php
@@ -38,6 +38,23 @@
 	));
 });
 
+it('declares scalar primary keys for api_plugin_db_table_create', function () {
+	// api_plugin_db_table_create() interpolates data['primary'] straight into
+	// PRIMARY KEY (`...`) down to the 1.2.29 compat floor, so an array would
+	// render as PRIMARY KEY (`Array`) and fail the create on a fresh install.
+	plugin_evidence_setup_database();
+
+	$withPrimary = array_filter($GLOBALS['__test_db_calls'], function ($call) {
+		return $call['fn'] === 'api_plugin_db_table_create' && isset($call['params']['primary']);
+	});
+
+	expect($withPrimary)->not->toBeEmpty();
+
+	foreach ($withPrimary as $call) {
+		expect($call['params']['primary'])->toBeString();
+	}
+});
+
 it('seeds the vendor-specific query catalog', function () {
 	plugin_evidence_setup_database();