diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder_findRootOf_Test.java b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder_findRootOf_Test.java
index 3e8fab7..be531f2 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder_findRootOf_Test.java
+++ b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder_findRootOf_Test.java
@@ -35,6 +35,10 @@
     assertThat(finder.findRootOf(null), nullValue());
   }
 
+  @Test public void should_return_null_if_path_is_empty() {
+    assertThat(finder.findRootOf(""), nullValue());
+  }
+
   @Test public void should_throw_error_if_path_does_not_contain_descriptor_FQN() {
     thrown.expect(IllegalArgumentException.class);
     thrown.expectMessage("Path '/usr/local/include' does not contain '/google/protobuf/descriptor.proto'");
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder.java
index 9fa8783..1e1dd46 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/builder/ProtoDescriptorPathFinder.java
@@ -9,6 +9,7 @@
 package com.google.eclipse.protobuf.ui.builder;
 
 import static com.google.eclipse.protobuf.scoping.ProtoDescriptor.DESCRIPTOR_IMPORT_URI;
+import static org.eclipse.xtext.util.Strings.isEmpty;
 
 /**
  * @author alruiz@google.com (Alex Ruiz)
@@ -18,7 +19,7 @@
   private static final String DESCRIPTOR_FQN = "/" + DESCRIPTOR_IMPORT_URI;
 
   public String findRootOf(String descriptorFilePath) {
-    if (descriptorFilePath == null) return null;
+    if (isEmpty(descriptorFilePath)) return null;
     int indexOfDescriptorFqn = descriptorFilePath.indexOf(DESCRIPTOR_FQN);
     if (indexOfDescriptorFqn == -1) {
       String format = "Path '%s' does not contain '%s'";