diff --git a/blocks-proc.js b/blocks-proc.js
index 8128482..a5894a3 100644
--- a/blocks-proc.js
+++ b/blocks-proc.js
@@ -25,6 +25,11 @@ const LIB_ICONS = {
 
 /** Procedure definition block with inputs/outputs/description/return-style. Lives in the Procedures tab. */
 class WCProcedure extends WCBlock {
+  delete() {
+    if (this.dataset.readonly) { showError("Cannot delete a library procedure."); return; }
+    super.delete();
+  }
+
   connectedCallback() {
     super.connectedCallback();
     this._el.naturalName = this._require(".proc-natural-name");
diff --git a/wcblock.js b/wcblock.js
index 29ac82e..49d38ea 100644
--- a/wcblock.js
+++ b/wcblock.js
@@ -46,7 +46,7 @@ class WCBlock extends HTMLElement {
     });
 
     const isAlgoBlock = !!this.closest("#draw-area");
-    if (!(this instanceof WCStart) && !(this instanceof WCEnd)) {
+    if (!(this instanceof WCStart) && !(this instanceof WCEnd) && !this.dataset.readonly) {
       const btn = document.createElement("button");
       btn.className = "delete-btn";
       btn.textContent = "\u00D7";