diff --git a/server/WORKLOG.md b/server/WORKLOG.md
index fe390aaa..09ffd399 100644
--- a/server/WORKLOG.md
+++ b/server/WORKLOG.md
@@ -33,9 +33,6 @@ strangle
 
 ## NOW
 * check zone completion
-* serialize modified stats
-  * remove spec from cryp
-  * dupe rare specs check
 
 ## SOON
 * clean up categories
diff --git a/server/src/cryp.rs b/server/src/cryp.rs
index fca92035..fdb6a338 100644
--- a/server/src/cryp.rs
+++ b/server/src/cryp.rs
@@ -295,7 +295,10 @@ impl Cryp {
                     return Err(format_err!("cryp at maximum rare specalisations ({:})", max_rare))
                 }
 
-                // check dupes
+                if self.specs.rare.iter().find(|s| s.spec == spec.spec).is_some() {
+                    return Err(format_err!("duplicate rare specialisation {:?}", spec.spec));
+                }
+
                 self.specs.rare.push(spec);
             },
         };