diff --git a/antlr3.changes b/antlr3.changes
index 9583b3e..02025dc 100644
--- a/antlr3.changes
+++ b/antlr3.changes
@@ -1,3 +1,12 @@
+-------------------------------------------------------------------
+Fri Sep 15 16:02:58 UTC 2023 - Fridrich Strba <fstrba@suse.com>
+
+- Added patches:
+  * reproducible-order.patch
+    + ensure reproducible elements order by sorting
+  * reproducible-timestamp.patch
+    + support SOURCE_DATE_EPOCH for generatedTimestamp 
+
 -------------------------------------------------------------------
 Fri Sep 15 08:19:19 UTC 2023 - Bernhard Wiedemann <bwiedemann@suse.com>
 
diff --git a/antlr3.spec b/antlr3.spec
index 9b803a0..66be845 100644
--- a/antlr3.spec
+++ b/antlr3.spec
@@ -37,6 +37,8 @@ Source0:        https://github.com/antlr/antlr3/archive/%{antlr_version}.tar.gz
 Patch0:         antlr3-java8-fix.patch
 # Generate OSGi metadata
 Patch1:         antlr3-osgi-manifest.patch
+Patch2:         reproducible-order.patch
+Patch3:         reproducible-timestamp.patch
 Patch100:       antlr3-generated_sources.patch
 BuildRequires:  fdupes
 BuildRequires:  java-devel >= 1.8
@@ -131,6 +133,8 @@ BuildArch:      noarch
 sed -i "s,\${buildNumber},`date -u -d@${SOURCE_DATE_EPOCH:-$(date +%%s)}`," tool/src/main/resources/org/antlr/antlr.properties
 %patch0 -p1
 %patch1
+%patch2 -p1
+%patch3 -p1
 
 # remove pre-built artifacts
 find -type f -a -name *.jar -delete
diff --git a/reproducible-order.patch b/reproducible-order.patch
new file mode 100644
index 0000000..ec6787f
--- /dev/null
+++ b/reproducible-order.patch
@@ -0,0 +1,30 @@
+--- antlr3-3.5.3/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g	2023-09-15 17:54:38.044172037 +0200
++++ antlr3-3.5.3/tool/src/main/antlr3/org/antlr/grammar/v3/CodeGenTreeWalker.g	2023-09-15 17:58:10.758972706 +0200
+@@ -56,6 +56,7 @@
+ import java.util.HashSet;
+ import java.util.Set;
+ import java.util.Collection;
++import java.util.Collections;
+ import org.antlr.runtime.BitSet;
+ import org.antlr.runtime.DFA;
+ import org.stringtemplate.v4.ST;
+@@ -284,6 +285,7 @@
+         }
+         labels.add( label );
+     }
++    Collections.sort(labels); // ensure reproducible order
+     return labels;
+ }
+ 
+--- antlr3-3.5.3/tool/src/main/java/org/antlr/Tool.java	2023-09-15 17:54:38.044172037 +0200
++++ antlr3-3.5.3/tool/src/main/java/org/antlr/Tool.java	2023-09-15 17:54:49.090915002 +0200
+@@ -1052,6 +1052,9 @@
+      */
+     public static String getCurrentTimeStamp() {
+         GregorianCalendar calendar = new java.util.GregorianCalendar();
++        if (System.getenv("SOURCE_DATE_EPOCH") != null) {
++            calendar.setTimeInMillis(1000 * Long.parseLong(System.getenv("SOURCE_DATE_EPOCH")));
++        }
+         int y = calendar.get(Calendar.YEAR);
+         int m = calendar.get(Calendar.MONTH) + 1; // zero-based for months
+         int d = calendar.get(Calendar.DAY_OF_MONTH);
diff --git a/reproducible-timestamp.patch b/reproducible-timestamp.patch
new file mode 100644
index 0000000..bf055c8
--- /dev/null
+++ b/reproducible-timestamp.patch
@@ -0,0 +1,12 @@
+--- antlr3-3.5.3/tool/src/main/java/org/antlr/Tool.java	2023-09-15 17:54:38.044172037 +0200
++++ antlr3-3.5.3/tool/src/main/java/org/antlr/Tool.java	2023-09-15 17:54:49.090915002 +0200
+@@ -1052,6 +1052,9 @@
+      */
+     public static String getCurrentTimeStamp() {
+         GregorianCalendar calendar = new java.util.GregorianCalendar();
++        if (System.getenv("SOURCE_DATE_EPOCH") != null) {
++            calendar.setTimeInMillis(1000 * Long.parseLong(System.getenv("SOURCE_DATE_EPOCH")));
++        }
+         int y = calendar.get(Calendar.YEAR);
+         int m = calendar.get(Calendar.MONTH) + 1; // zero-based for months
+         int d = calendar.get(Calendar.DAY_OF_MONTH);