diff --git a/ecj.spec b/ecj.spec
index ba80e21..41bf100 100644
--- a/ecj.spec
+++ b/ecj.spec
@@ -1,11 +1,11 @@
 Epoch: 1
 
-%global qualifier R-4.7.1-201709061700
+%global qualifier M-4.7.3-201803010715
 
 Summary: Eclipse Compiler for Java
 Name: ecj
-Version: 4.7.1
-Release: 2%{?dist}
+Version: 4.7.3
+Release: 1%{?dist}
 URL: http://www.eclipse.org
 License: EPL
 
@@ -21,6 +21,9 @@ Patch0: %{name}-rpmdebuginfo.patch
 # Fix build with lambda syntax, ebz#520940
 Patch1: java8.patch
 
+# Include java9api stubs in build
+Patch2: java9api.patch
+
 BuildArch: noarch
 
 BuildRequires: ant
@@ -34,6 +37,7 @@ the JDT Core batch compiler.
 %setup -q -c
 %patch0 -p1
 %patch1 -p3
+%patch2 -b.orig
 
 sed -i -e 's|debuglevel=\"lines,source\"|debug=\"yes\"|g' build.xml
 sed -i -e "s/Xlint:none/Xlint:none -encoding cp1252/g" build.xml
@@ -55,7 +59,7 @@ rm -f org/eclipse/jdt/core/JDTCompilerAdapter.java
   org.eclipse.jdt:core org.eclipse.jdt:ecj
 
 %build
-ant 
+ant -Djava9api=$(build-classpath eclipse/java9api)
 
 %install
 %mvn_artifact pom.xml ecj.jar
@@ -74,6 +78,9 @@ install -m 644 -p ecj.1 $RPM_BUILD_ROOT%{_mandir}/man1/ecj.1
 %{_mandir}/man1/ecj*
 
 %changelog
+* Tue Mar 20 2018 Mat Booth <mat.booth@redhat.com> - 1:4.7.3-1
+- Update to Oxygen.3
+
 * Wed Feb 07 2018 Fedora Release Engineering <releng@fedoraproject.org> - 1:4.7.1-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_28_Mass_Rebuild
 
diff --git a/java9api.patch b/java9api.patch
new file mode 100644
index 0000000..02159f5
--- /dev/null
+++ b/java9api.patch
@@ -0,0 +1,48 @@
+--- build.xml.orig	2018-03-20 15:15:57.063810672 +0000
++++ build.xml	2018-03-20 15:16:26.018700633 +0000
+@@ -15,16 +15,20 @@
+ 	<property name="output" value="bin" />
+ 	<property name="jar_file" value="ecj.jar" />
+ 
++	<path id="build.path">
++		<pathelement path="${java9api}"/>
++		<pathelement path="/usr/lib/jvm/java-1.8.0/jre/lib/rt.jar"/>
++	</path>
+ 	<target name="build">
+ 		<delete file="${basedir}/${jar_file}" failonerror="no" />
+ 		<delete dir="${output}" failonerror="no" />
+ 		<mkdir dir="${output}" />
+ 
+-		<javac srcdir="${basedir}" destdir="${output}"
+-					debuglevel="lines,source"
++		<javac srcdir="${basedir}" destdir="${output}" bootclasspathref="build.path"
++					debug="yes"
+ 					source="1.8"
+ 					target="1.8">
+-			<compilerarg line="-Xlint:none"/>
++			<compilerarg line="-Xlint:none -encoding cp1252 -encoding cp1252"/>
+ 		</javac>
+ 
+ 		<delete file="${basedir}/META-INF/MANIFEST.MF" failonerror="false"/>
+--- org/eclipse/jdt/internal/compiler/env/IModulePathEntry.java.orig	2018-03-20 15:38:22.373710813 +0000
++++ org/eclipse/jdt/internal/compiler/env/IModulePathEntry.java	2018-03-20 15:39:46.541393267 +0000
+@@ -10,7 +10,6 @@
+  *******************************************************************************/
+ package org.eclipse.jdt.internal.compiler.env;
+ 
+-import org.eclipse.jdt.core.IJavaProject;
+ import org.eclipse.jdt.core.compiler.CharOperation;
+ 
+ /**
+@@ -80,9 +79,4 @@
+ 	public default boolean isAutomaticModule() {
+ 		return false;
+ 	}
+-
+-	/** Tests whether the current entry represents the given java project. */
+-	public default boolean equalsProject(IJavaProject project) {
+-		return false;
+-	}
+-}
+\ No newline at end of file
++}
diff --git a/sources b/sources
index bf574ca..6a090ae 100644
--- a/sources
+++ b/sources
@@ -1,2 +1,2 @@
-SHA512 (ecj-4.7.1.pom) = 2f670ac1b1fefa73ae73a56b99b374bc1c3c31944e667f39c0a16cae2580e754f2ba3f6b2ec5234cf1ab03d63743f71a0912a4919772b37fe7b4f37fbd9593d8
-SHA512 (ecjsrc-4.7.1.jar) = d4ec9be4c7e3f6b5072dad58219b98475def366d45953a92e7fedfa7b316522a377a19a2733e81411e1bb072db7fdf27fd420d2db4229b225349adc27dcaacd9
+SHA512 (ecjsrc-4.7.3.jar) = 31a86941360fca6a9e93216acf3f66ea27d66b955ffefed7f2b160685ac0d26111e8eaf0fecfd4972f48112970d1501cf60aed121c67c55f007b313706490688
+SHA512 (ecj-4.7.3.pom) = 79e59064806c2c4a2ed62da3a584448bbd3603bc1e7fab73f0d5b34dffec8ff8305604e1786e8e5fbf41204a4e336e3268d862158986fea0d4cbd81bb1158d32