diff --git a/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/MissionModelBuilder.java b/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/MissionModelBuilder.java
index 4818d5cf0e..240a31dd7b 100644
--- a/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/MissionModelBuilder.java
+++ b/merlin-driver/src/main/java/gov/nasa/jpl/aerie/merlin/driver/MissionModelBuilder.java
@@ -118,6 +118,7 @@ CellId<State> allocate(
 
     @Override
     public void resource(final String name, final Resource<?> resource) {
+      if (this.resources.containsKey(name)) throw new IllegalArgumentException("A resource with that name has already been declared: \"" + name + "\"");
       this.resources.put(name, resource);
     }