--- a/src/main/java/org/apache/maven/plugins/javadoc/AbstractJavadocMojo.java
+++ b/src/main/java/org/apache/maven/plugins/javadoc/AbstractJavadocMojo.java
@@ -2692,6 +2692,14 @@ public abstract class AbstractJavadocMojo extends AbstractMojo {
     private String getBottomText() {
         final String inceptionYear = project.getInceptionYear();
 
+        if ( outputTimestamp == null ||
+            outputTimestamp.length() < 1 ||
+            ( ( outputTimestamp.length() == 1 )
+                && !Character.isDigit( outputTimestamp.charAt(0) ) ) )
+        {
+            outputTimestamp = System.getenv("SOURCE_DATE_EPOCH");
+        }
+
         // get Reproducible Builds outputTimestamp date value or the current local date.
         final LocalDate localDate = MavenArchiver.parseBuildOutputTimestamp(outputTimestamp)
                 .map(instant -> instant.atZone(ZoneOffset.UTC).toLocalDate())