diff --git a/admin/environment.xml b/admin/environment.xml
index fbda3f32022..40e66be21ff 100644
--- a/admin/environment.xml
+++ b/admin/environment.xml
@@ -2097,6 +2097,7 @@
       <VENDOR name="oracle" version="10.2" />
     </DATABASE>
     <PHP version="7.0.0" level="required">
+      <RESTRICT function="restrict_php_version_73" message="unsupportedphpversion73" />
     </PHP>
     <PCREUNICODE level="optional">
       <FEEDBACK>
@@ -2273,6 +2274,7 @@
       <VENDOR name="oracle" version="10.2" />
     </DATABASE>
     <PHP version="7.0.0" level="required">
+      <RESTRICT function="restrict_php_version_73" message="unsupportedphpversion73" />
     </PHP>
     <PCREUNICODE level="optional">
       <FEEDBACK>
diff --git a/lang/en/admin.php b/lang/en/admin.php
index 1c93d92f1a8..2616cd824da 100644
--- a/lang/en/admin.php
+++ b/lang/en/admin.php
@@ -1206,6 +1206,7 @@ $string['unsupporteddbtablerowformat'] = 'Your database has tables using Antelop
 $string['unsupportedphpversion7'] = 'PHP version 7 is not supported.';
 $string['unsupportedphpversion71'] = 'PHP version 7.1 is not supported.';
 $string['unsupportedphpversion72'] = 'PHP version 7.2 is not supported.';
+$string['unsupportedphpversion73'] = 'PHP version 7.3 is not supported.';
 $string['unsuspenduser'] = 'Activate user account';
 $string['updateaccounts'] = 'Update existing accounts';
 $string['updatecomponent'] = 'Update component';
diff --git a/lib/environmentlib.php b/lib/environmentlib.php
index 51ea48db52e..dbf2520b255 100644
--- a/lib/environmentlib.php
+++ b/lib/environmentlib.php
@@ -1617,3 +1617,14 @@ function restrict_php_version_71(&$result) {
 function restrict_php_version_72(&$result) {
     return restrict_php_version($result, '7.2');
 }
+
+/**
+ * Check if the current PHP version is greater than or equal to
+ * PHP version 7.3.
+ *
+ * @param object $result an environment_results instance
+ * @return bool result of version check
+ */
+function restrict_php_version_73(&$result) {
+    return restrict_php_version($result, '7.3');
+}