diff --git a/antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java b/antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java
index a333b81f8..f0bbb8998 100644
--- a/antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java
+++ b/antlr4-maven-plugin/src/main/java/org/antlr/mojo/antlr4/Antlr4Mojo.java
@@ -466,7 +466,7 @@ public class Antlr4Mojo
             throws TokenStreamException, RecognitionException, IOException, InclusionScanException {
         // Which files under the source set should we be looking for as grammar files
         //
-        SourceMapping mapping = new SuffixMapping("g4", Collections.EMPTY_SET);
+        SourceMapping mapping = new SuffixMapping("g4", Collections.<String>emptySet());
 
         // What are the sets of includes (defaulted or otherwise).
         //