diff --git a/plugins/org.eclipse.justj.codegen/src/org/eclipse/justj/codegen/templates/plugin/P2Inf.java b/plugins/org.eclipse.justj.codegen/src/org/eclipse/justj/codegen/templates/plugin/P2Inf.java
index b80a484..bd34432 100644
--- a/plugins/org.eclipse.justj.codegen/src/org/eclipse/justj/codegen/templates/plugin/P2Inf.java
+++ b/plugins/org.eclipse.justj.codegen/src/org/eclipse/justj/codegen/templates/plugin/P2Inf.java
@@ -26,25 +26,48 @@
 
   public final String NL = nl == null ? (System.getProperties().getProperty("line.separator")) : nl;
   protected static final String _1 = "#";
-  protected static final String _2 = "# Ensure that the applicable implementation fragment gets installed automatically.";
-  protected static final String _3 = ")(!(";
-  protected static final String _4 = ")(osgi.arch=";
-  protected static final String _5 = ".";
-  protected static final String _6 = ".buildtime=true)))";
-  protected static final String _7 = ".filter = (&(osgi.os=";
-  protected static final String _8 = ".name = ";
-  protected static final String _9 = ".namespace = org.eclipse.equinox.p2.iu";
-  protected static final String _10 = ".range = [$version$,$version$]";
-  protected static final String _11 = "properties.0.name = org.eclipse.justj.model";
-  protected static final String _12 = "properties.0.value = ";
-  protected static final String _13 = "requires.";
-  protected final String _14 = "";
-  protected final String _15 = NL + _1 + NL + _2 + NL;
-  protected final String _16 = NL + NL + _13;
-  protected final String _17 = _9 + NL + _13;
-  protected final String _18 = NL + _13;
-  protected final String _19 = _10 + NL + _13;
-  protected final String _20 = NL + NL + _11 + NL + _12;
+  protected static final String _2 = "# Declare a capability that can be used to ensure mutually exclusive installation of IUs that set the -vm option.";
+  protected static final String _3 = "# Ensure that the applicable implementation fragment gets installed automatically.";
+  protected static final String _4 = "# Exclude all other providers of this capability; the site depends on all the feautres so exclude this requirement at build time.";
+  protected static final String _5 = "# Exclude the synthetic a.jre IUs from the p2 repositories; Tycho gets confused by negative requirements so filter this to avoid it at build time.";
+  protected static final String _6 = "# Exclude the synthetic a.jre.javase IUs from the p2 repositories; Tycho gets confused by negative requirements so filter this to avoid it at build time.";
+  protected static final String _7 = "' && x.namespace == 'org.eclipse.equinox.p2.iu')";
+  protected static final String _8 = ")(!(";
+  protected static final String _9 = ")(osgi.arch=";
+  protected static final String _10 = ".";
+  protected static final String _11 = ".buildtime=true))";
+  protected static final String _12 = ".buildtime=true)))";
+  protected static final String _13 = ".filter = (!(";
+  protected static final String _14 = ".filter = (&(osgi.os=";
+  protected static final String _15 = ".matchExp = providedCapabilities.exists(x | x.name == 'jre' && x.namespace == 'org.eclipse.justj') && !providedCapabilities.exists(x | x.name == '";
+  protected static final String _16 = ".max = 0";
+  protected static final String _17 = ".min = 0";
+  protected static final String _18 = ".name = ";
+  protected static final String _19 = ".name = a.jre";
+  protected static final String _20 = ".name = a.jre.javase";
+  protected static final String _21 = ".namespace = org.eclipse.equinox.p2.iu";
+  protected static final String _22 = ".range = [$version$,$version$]";
+  protected static final String _23 = "properties.0.name = org.eclipse.justj.model";
+  protected static final String _24 = "properties.0.value = ";
+  protected static final String _25 = "provides.0.name = jre";
+  protected static final String _26 = "provides.0.namespace = org.eclipse.justj";
+  protected static final String _27 = "provides.0.version = $version$";
+  protected static final String _28 = "requires.";
+  protected final String _29 = "";
+  protected final String _30 = NL + _1 + NL + NL + _3 + NL;
+  protected final String _31 = NL + _28;
+  protected final String _32 = _21 + NL + _28;
+  protected final String _33 = _22 + NL + _28;
+  protected final String _34 = _12 + NL;
+  protected final String _35 = NL + _5;
+  protected final String _36 = _19 + NL + _28;
+  protected final String _37 = _17 + NL + _28;
+  protected final String _38 = _16 + NL + _28;
+  protected final String _39 = _11 + NL + NL + _6;
+  protected final String _40 = _20 + NL + _28;
+  protected final String _41 = _11 + NL + NL + _2 + NL + _26 + NL + _25 + NL + _27 + NL + NL + _4;
+  protected final String _42 = _7 + NL + _28;
+  protected final String _43 = _11 + NL + NL + _23 + NL + _24;
 
   public String generate(Object argument)
   {
@@ -54,37 +77,79 @@
   Model model = jvm.getModel();
   String modelName = model.getName();
   String fullName = modelName + '.' + jvmName;
-    builder.append(_14);
+    builder.append(_29);
     builder.append(org.eclipse.justj.codegen.model.util.Generator.getCopyright(argument, "# ", NL));
-    builder.append(_15);
+    builder.append(_30);
     int count = 0;
   for (Variant variant : jvm.getVariants()) {
     ++count;
     String os = variant.getOs();
     String arch = variant.getArch();
-    builder.append(_16);
+    builder.append(_31);
     builder.append(count);
-    builder.append(_17);
+    builder.append(_32);
     builder.append(count);
-    builder.append(_8);
-    builder.append(fullName);
-    builder.append(_5);
-    builder.append(os);
-    builder.append(_5);
-    builder.append(arch);
     builder.append(_18);
-    builder.append(count);
-    builder.append(_19);
-    builder.append(count);
-    builder.append(_7);
+    builder.append(fullName);
+    builder.append(_10);
     builder.append(os);
-    builder.append(_4);
+    builder.append(_10);
     builder.append(arch);
-    builder.append(_3);
+    builder.append(_31);
+    builder.append(count);
+    builder.append(_33);
+    builder.append(count);
+    builder.append(_14);
+    builder.append(os);
+    builder.append(_9);
+    builder.append(arch);
+    builder.append(_8);
     builder.append(modelName);
-    builder.append(_6);
+    builder.append(_34);
     }
-    builder.append(_20);
+    builder.append(_35);
+    ++count;
+    builder.append(_31);
+    builder.append(count);
+    builder.append(_32);
+    builder.append(count);
+    builder.append(_36);
+    builder.append(count);
+    builder.append(_37);
+    builder.append(count);
+    builder.append(_38);
+    builder.append(count);
+    builder.append(_13);
+    builder.append(modelName);
+    builder.append(_39);
+    ++count;
+    builder.append(_31);
+    builder.append(count);
+    builder.append(_32);
+    builder.append(count);
+    builder.append(_40);
+    builder.append(count);
+    builder.append(_37);
+    builder.append(count);
+    builder.append(_38);
+    builder.append(count);
+    builder.append(_13);
+    builder.append(modelName);
+    builder.append(_41);
+    ++count;
+    builder.append(_31);
+    builder.append(count);
+    builder.append(_15);
+    builder.append(fullName);
+    builder.append(_42);
+    builder.append(count);
+    builder.append(_37);
+    builder.append(count);
+    builder.append(_38);
+    builder.append(count);
+    builder.append(_13);
+    builder.append(modelName);
+    builder.append(_43);
     builder.append(Generator.getModelXMLAsPropertyValue(jvm, NL));
     builder.append(NL);
     return builder.toString();
diff --git a/plugins/org.eclipse.justj.codegen/templates/plugin/p2.inf.jet b/plugins/org.eclipse.justj.codegen/templates/plugin/p2.inf.jet
index 58240de..a16780e 100644
--- a/plugins/org.eclipse.justj.codegen/templates/plugin/p2.inf.jet
+++ b/plugins/org.eclipse.justj.codegen/templates/plugin/p2.inf.jet
@@ -15,6 +15,7 @@
   String modelName = model.getName();
   String fullName = modelName + '.' + jvmName;%>
 <%@include file="../copyright.properties.jetinc"%>
+
 # Ensure that the applicable implementation fragment gets installed automatically.
 
 <%int count = 0;
@@ -22,12 +23,39 @@
     ++count;
     String os = variant.getOs();
     String arch = variant.getArch();%>
-
 requires.<%=count%>.namespace = org.eclipse.equinox.p2.iu
 requires.<%=count%>.name = <%=fullName%>.<%=os%>.<%=arch%>
 requires.<%=count%>.range = [$version$,$version$]
 requires.<%=count%>.filter = (&(osgi.os=<%=os%>)(osgi.arch=<%=arch%>)(!(<%=modelName%>.buildtime=true)))
+
 <%}%>
+# Exclude the synthetic a.jre IUs from the p2 repositories; Tycho gets confused by negative requirements so filter this to avoid it at build time.
+<%++count;%>
+requires.<%=count%>.namespace = org.eclipse.equinox.p2.iu
+requires.<%=count%>.name = a.jre
+requires.<%=count%>.min = 0
+requires.<%=count%>.max = 0
+requires.<%=count%>.filter = (!(<%=modelName%>.buildtime=true))
+
+# Exclude the synthetic a.jre.javase IUs from the p2 repositories; Tycho gets confused by negative requirements so filter this to avoid it at build time.
+<%++count;%>
+requires.<%=count%>.namespace = org.eclipse.equinox.p2.iu
+requires.<%=count%>.name = a.jre.javase
+requires.<%=count%>.min = 0
+requires.<%=count%>.max = 0
+requires.<%=count%>.filter = (!(<%=modelName%>.buildtime=true))
+
+# Declare a capability that can be used to ensure mutually exclusive installation of IUs that set the -vm option.
+provides.0.namespace = org.eclipse.justj
+provides.0.name = jre
+provides.0.version = $version$
+
+# Exclude all other providers of this capability; the site depends on all the feautres so exclude this requirement at build time.
+<%++count;%>
+requires.<%=count%>.matchExp = providedCapabilities.exists(x | x.name == 'jre' && x.namespace == 'org.eclipse.justj') && !providedCapabilities.exists(x | x.name == '<%=fullName%>' && x.namespace == 'org.eclipse.equinox.p2.iu')
+requires.<%=count%>.min = 0
+requires.<%=count%>.max = 0
+requires.<%=count%>.filter = (!(<%=modelName%>.buildtime=true))
 
 properties.0.name = org.eclipse.justj.model
 properties.0.value = <%=Generator.getModelXMLAsPropertyValue(jvm, NL)%>