diff --git a/.travis.yml b/.travis.yml
index 18bbdb5..2ecea4a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,28 +4,57 @@ sudo: false
 
 matrix:
   include:
+    - php: 7.2
     - php: 7.1
     - php: 7.0
     - php: 5.6
     - php: 5.5
     - php: 5.4
-    - php: hhvm
 
 before_install:
-    # Setup WP_TESTS_DIR (needed to bootstrap WP PHPUnit tests). 
-    - export WP_TESTS_DIR=/tmp/wordpress/tests/phpunit/
-    # Clone the WordPress develop repo.
-    - git clone --depth=1 --branch="4.3" git://develop.git.wordpress.org/ /tmp/wordpress/
-    # Setup DB.
-    - mysql -e "CREATE DATABASE wordpress_test;" -uroot
-    # Setup wp-config.
-    - cp /tmp/wordpress/wp-tests-config-sample.php /tmp/wordpress/wp-tests-config.php
-    - sed -i "s/youremptytestdbnamehere/wordpress_test/" /tmp/wordpress/wp-tests-config.php
-    - sed -i "s/yourusernamehere/root/" /tmp/wordpress/wp-tests-config.php
-    - sed -i "s/yourpasswordhere//" /tmp/wordpress/wp-tests-config.php
+  # Setup WP_TESTS_DIR (needed to bootstrap WP PHPUnit tests).
+  - export WP_TESTS_DIR=/tmp/wordpress/tests/phpunit/
+  # http serves a single offer, whereas https serves multiple. we only want one
+  - curl -s http://api.wordpress.org/core/version-check/1.7/ > /tmp/wp-latest.json
+  - WP_VERSION=$(grep -o '"version":"[^"]*' /tmp/wp-latest.json | sed 's/"version":"//')
+  - printf "Cloning WordPress %s\n" "$WP_VERSION"
+  # Clone the WordPress develop repo.
+  - git clone --depth=1 --branch="$WP_VERSION" git://develop.git.wordpress.org/ /tmp/wordpress/
+  # Setup DB.
+  - mysql -e "CREATE DATABASE wordpress_test;" -uroot
+  # Setup wp-config.
+  - cp /tmp/wordpress/wp-tests-config-sample.php /tmp/wordpress/wp-tests-config.php
+  - sed -i "s/youremptytestdbnamehere/wordpress_test/" /tmp/wordpress/wp-tests-config.php
+  - sed -i "s/yourusernamehere/root/" /tmp/wordpress/wp-tests-config.php
+  - sed -i "s/yourpasswordhere//" /tmp/wordpress/wp-tests-config.php
 
 install: composer install --no-dev
 
+before_script:
+  - |
+    # Export Composer's global bin dir to PATH, but not on PHP 5.2:
+    if [[ ${TRAVIS_PHP_VERSION:0:3} != "5.2" ]]; then
+      composer config --list --global
+      export PATH=`composer config --list --global | grep '\[home\]' | { read a; echo "${a#* }/vendor/bin:$PATH"; }`
+    fi
+  - |
+    # Install the specified version of PHPUnit depending on the PHP version:
+    case "$TRAVIS_PHP_VERSION" in
+      7.3|7.2|7.1|7.0|nightly)
+        echo "Using PHPUnit 6.x"
+        travis_retry composer global require "phpunit/phpunit:^6"
+        # See trac ticket #43218 for when we can use PHPUnit 7
+        ;;
+      5.6|5.5|5.4|5.3)
+        echo "Using PHPUnit 4.x"
+        travis_retry composer global require "phpunit/phpunit:^4"
+        ;;
+      *)
+        echo "No PHPUnit version handling for PHP version $TRAVIS_PHP_VERSION"
+        exit 1
+        ;;
+    esac
+
 script:
   - phpunit
 
diff --git a/lib/class-file-reflector.php b/lib/class-file-reflector.php
index 5b01e8d..62f401d 100644
--- a/lib/class-file-reflector.php
+++ b/lib/class-file-reflector.php
@@ -171,7 +171,10 @@ public function leaveNode( \PHPParser_Node $node ) {
 				break;
 
 			case 'Stmt_Function':
-				end( $this->functions )->uses = array_pop( $this->location )->uses;
+				$function = array_pop( $this->location );
+				if ( isset( $function->uses ) && ! empty( $function->uses ) ) {
+					end( $this->functions )->uses = $function->uses;
+				}
 				break;
 
 			case 'Stmt_ClassMethod':