diff --git a/build/org.eclipse.pde.build/src/org/eclipse/pde/internal/build/site/PDEState.java b/build/org.eclipse.pde.build/src/org/eclipse/pde/internal/build/site/PDEState.java
index 6912a54bec..ce1f6eea12 100644
--- a/build/org.eclipse.pde.build/src/org/eclipse/pde/internal/build/site/PDEState.java
+++ b/build/org.eclipse.pde.build/src/org/eclipse/pde/internal/build/site/PDEState.java
@@ -492,6 +492,9 @@ public static String querySystemPackages(IExecutionEnvironment environment) {
 	}
 
 	private static IVMInstall bestVmInstallFor(IExecutionEnvironment environment) {
+		if (environment == null) {
+			return null;
+		}
 		IVMInstall defaultVM = environment.getDefaultVM();
 		if (defaultVM != null) {
 			return defaultVM;