diff --git a/hollow/src/main/java/com/netflix/hollow/api/codegen/HollowAPIGenerator.java b/hollow/src/main/java/com/netflix/hollow/api/codegen/HollowAPIGenerator.java
index 5eae7d15bc..67c0b81e21 100644
--- a/hollow/src/main/java/com/netflix/hollow/api/codegen/HollowAPIGenerator.java
+++ b/hollow/src/main/java/com/netflix/hollow/api/codegen/HollowAPIGenerator.java
@@ -233,6 +233,13 @@ public Builder withGetterPrefix(String getterPrefix) {
         }
         
         public HollowAPIGenerator build() {
+            if(apiClassname == null)
+                throw new IllegalStateException("Please specify an API classname (.withAPIClassname()) before calling .build()");
+            if(packageName == null)
+                throw new IllegalStateException("Please specify a package name (.withPackageName()) before calling .build()");
+            if(dataset == null)
+                throw new IllegalStateException("Please specify a data model (.withDataModel()) before calling .build()");
+            
             HollowAPIGenerator generator = new HollowAPIGenerator(apiClassname, packageName, dataset, parameterizedTypes, parameterizeAllClassnames);
             generator.setClassPostfix(classPostfix);
             generator.setGetterPrefix(getterPrefix);