diff --git a/pitest-aggregator/src/main/java/org/pitest/aggregate/ReportAggregator.java b/pitest-aggregator/src/main/java/org/pitest/aggregate/ReportAggregator.java
index 6bb783d02..f5f217b43 100644
--- a/pitest-aggregator/src/main/java/org/pitest/aggregate/ReportAggregator.java
+++ b/pitest-aggregator/src/main/java/org/pitest/aggregate/ReportAggregator.java
@@ -159,7 +159,11 @@ public Builder lineCoverageFiles(final List<File> lineCoverageFiles) {
 
     public Builder addLineCoverageFile(final File lineCoverageFile) {
       validateFile(lineCoverageFile);
-      this.lineCoverageFiles.add(lineCoverageFile);
+      if (lineCoverageFile.exists()) {
+        this.lineCoverageFiles.add(lineCoverageFile);
+      } else {
+        LOG.info("ignoring absent line coverage file " + lineCoverageFile.getAbsolutePath());
+      }
       return this;
     }
 
@@ -173,7 +177,11 @@ public Builder mutationResultsFiles(final List<File> mutationResultsFiles) {
 
     public Builder addMutationResultsFile(final File mutationResultsFile) {
       validateFile(mutationResultsFile);
-      this.mutationResultsFiles.add(mutationResultsFile);
+      if (mutationResultsFile.exists()) {
+        this.mutationResultsFiles.add(mutationResultsFile);
+      } else {
+        LOG.info("ignoring absent mutation results file " + mutationResultsFile.getAbsolutePath());
+      }
       return this;
     }
 
@@ -273,8 +281,9 @@ private void validateFile(final File file) {
       if (file == null) {
         throw new IllegalArgumentException("file is null");
       }
-      if (!file.exists() || !file.isFile()) {
-        throw new IllegalArgumentException(file.getAbsolutePath() + " does not exist or is not a file");
+      // a non existent file shouldn't prevent the aggregator from being built
+      if (file.exists() && !file.isFile()) {
+        throw new IllegalArgumentException(file.getAbsolutePath() + "is not a file");
       }
     }
 
diff --git a/pitest-aggregator/src/test/java/org/pitest/aggregate/ReportAggregatorBuilderTest.java b/pitest-aggregator/src/test/java/org/pitest/aggregate/ReportAggregatorBuilderTest.java
index 0f4905833..26e420097 100644
--- a/pitest-aggregator/src/test/java/org/pitest/aggregate/ReportAggregatorBuilderTest.java
+++ b/pitest-aggregator/src/test/java/org/pitest/aggregate/ReportAggregatorBuilderTest.java
@@ -22,7 +22,7 @@
 
 public class ReportAggregatorBuilderTest {
 
-  private static final String NOT_A_FILE = "does not exist or is not a file";
+  private static final String NOT_A_FILE = "is not a file";
   private static final String NOT_A_DIR  = "is not a directory";
   private static final String IS_NULL    = "is null";
   @Rule
@@ -38,10 +38,10 @@ public void testLineCoverageFiles_withNull() {
 
   @Test
   public void testLineCoverageFiles_withFake() {
-    this.expected.expect(IllegalArgumentException.class);
-    this.expected.expectMessage(Matchers.containsString(NOT_A_FILE));
+    ReportAggregator.Builder builder = ReportAggregator.builder()
+        .lineCoverageFiles(Arrays.asList(new File("doesnotexist.xml")));
 
-    ReportAggregator.builder().lineCoverageFiles(Arrays.asList(new File("doesnotexist.xml")));
+    assertTrue(builder.getMutationResultsFiles().isEmpty());
   }
 
   @Test
@@ -62,10 +62,10 @@ public void testMutationResultsFiles_withNull() {
 
   @Test
   public void testMutationResultsFiles_withFake() {
-    this.expected.expect(IllegalArgumentException.class);
-    this.expected.expectMessage(Matchers.containsString(NOT_A_FILE));
+    ReportAggregator.Builder builder = ReportAggregator.builder()
+        .mutationResultsFiles(Arrays.asList(new File("doesnotexist.xml")));
 
-    ReportAggregator.builder().mutationResultsFiles(Arrays.asList(new File("doesnotexist.xml")));
+    assertTrue(builder.getMutationResultsFiles().isEmpty());
   }
 
   @Test