diff --git a/src/wp-includes/ms-functions.php b/src/wp-includes/ms-functions.php
index 49f55cfa8d..dc92eb3cbd 100644
--- a/src/wp-includes/ms-functions.php
+++ b/src/wp-includes/ms-functions.php
@@ -2296,7 +2296,7 @@ function get_space_allowed() {
 	if ( ! is_numeric( $space_allowed ) )
 		$space_allowed = get_site_option( 'blog_upload_space' );
 
-	if ( empty( $space_allowed ) || ! is_numeric( $space_allowed ) )
+	if ( ! is_numeric( $space_allowed ) )
 		$space_allowed = 100;
 
 	/**
diff --git a/tests/phpunit/tests/multisite/getSpaceAllowed.php b/tests/phpunit/tests/multisite/getSpaceAllowed.php
index 069201ad85..6470f38592 100644
--- a/tests/phpunit/tests/multisite/getSpaceAllowed.php
+++ b/tests/phpunit/tests/multisite/getSpaceAllowed.php
@@ -94,10 +94,10 @@ class Tests_Multisite_Get_Space_Allowed extends WP_UnitTestCase {
 			array( false, false, 100 ),
 			array( 'NAN', 'NAN', 100 ),
 
-			// These are likely unexpected.
-			array( 0,     666,   100 ),
-			array( false, 0,     100 ),
-			array( 'NAN', 0,     100 ),
+			// These effectively disable uploads.
+			array( 0,     666,   0 ),
+			array( false, 0,     0 ),
+			array( 'NAN', 0,     0 ),
 		);
 	}
 
diff --git a/tests/phpunit/tests/multisite/isUploadSpaceAvailable.php b/tests/phpunit/tests/multisite/isUploadSpaceAvailable.php
index 36be275944..d2abfd2337 100644
--- a/tests/phpunit/tests/multisite/isUploadSpaceAvailable.php
+++ b/tests/phpunit/tests/multisite/isUploadSpaceAvailable.php
@@ -102,7 +102,7 @@ class Tests_Multisite_Is_Upload_Space_Available extends WP_UnitTestCase {
 		$available = is_upload_space_available();
 		remove_filter( 'pre_get_space_used', array( $this, '_filter_space_used_small' ) );
 
-		$this->assertTrue( $available );
+		$this->assertFalse( $available );
 	}
 
 	function test_is_upload_space_available_upload_space_negative() {