diff --git a/findbugs/src/java/edu/umd/cs/findbugs/detect/RedundantInterfaces.java b/findbugs/src/java/edu/umd/cs/findbugs/detect/RedundantInterfaces.java
index 7b55a396d6..df8de4432e 100644
--- a/findbugs/src/java/edu/umd/cs/findbugs/detect/RedundantInterfaces.java
+++ b/findbugs/src/java/edu/umd/cs/findbugs/detect/RedundantInterfaces.java
@@ -58,7 +58,7 @@ public void visitClassContext(ClassContext classContext) {
             SortedSet<String> redundantInfNames = new TreeSet<String>();
 
             for (String interfaceName : interfaceNames) {
-                if (!"java/io/Serializable".equals(interfaceName)) {
+                if (!"java.io.Serializable".equals(interfaceName)) {
                     JavaClass inf = Repository.lookupClass(interfaceName.replace('/', '.'));
                     if (superObj.instanceOf(inf)) {
                         redundantInfNames.add(inf.getClassName());
diff --git a/findbugsTestCases/src/java/ghIssues/Issue0049.java b/findbugsTestCases/src/java/ghIssues/Issue0049.java
new file mode 100644
index 0000000000..eb788faeeb
--- /dev/null
+++ b/findbugsTestCases/src/java/ghIssues/Issue0049.java
@@ -0,0 +1,33 @@
+
+import java.io.Serializable;
+
+import edu.umd.cs.findbugs.annotations.ExpectWarning;
+import edu.umd.cs.findbugs.annotations.NoWarning;
+
+public class Issue0049 {
+    public interface TestInterface {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SuperClass implements TestInterface {}
+
+    @ExpectWarning("RI_REDUNDANT_INTERFACES")
+    public static class SubClassWithDuplicate extends SuperClass implements TestInterface {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SubClassWithoutDuplicate extends SuperClass {}
+
+    @ExpectWarning("RI_REDUNDANT_INTERFACES")
+    public static class SubSubClassWithDuplicate extends SubClassWithoutDuplicate implements TestInterface {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SerializableSuperClass implements Serializable {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SerializableSubClassWithDuplicate extends SerializableSuperClass implements Serializable {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SerializableSubClassWithoutDuplicate extends SerializableSuperClass {}
+
+    @NoWarning("RI_REDUNDANT_INTERFACES")
+    public static class SerializableSubSubClassDuplicate extends SerializableSubClassWithoutDuplicate implements Serializable {}
+}