diff --git a/ChangeLog.md b/ChangeLog.md
index 5e4e183..10e029a 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,6 +1,7 @@
 #2.2.17
   * Add mass as potential SCB modification
   * Fix mining laser statistics
+  * Remove non-existent grade 4 and 5 wake scanner modifications
 
 #2.2.16
   * Fix incorrect thermal load modifiers for dirty drives
diff --git a/modifications/modules.json b/modifications/modules.json
index eb5c9d3..c6ff877 100644
--- a/modifications/modules.json
+++ b/modifications/modules.json
@@ -842,9 +842,9 @@
   },
   "ws": {
     "blueprints": {
-      "WakeScanner_LightWeight": [1, 2, 3, 4, 5],
-      "WakeScanner_Reinforced": [1, 2, 3, 4, 5],
-      "WakeScanner_Shielded": [1, 2, 3, 4, 5]
+      "WakeScanner_LightWeight": [1, 2, 3],
+      "WakeScanner_Reinforced": [1, 2, 3],
+      "WakeScanner_Shielded": [1, 2, 3]
     },
     "modifications": [
       "boot",
diff --git a/spec/data-spec.js b/spec/data-spec.js
index a52cdfe..8d41d2e 100644
--- a/spec/data-spec.js
+++ b/spec/data-spec.js
@@ -203,7 +203,19 @@ describe('JSON Data', function() {
       expect(modification.method).toBeDefined('Modification has no method, ID:' + modification.id);
       ids[modification.id] = true;
     }
+  });
 
+  it('has valid module modifications', function() {
+    for (var m in Modifications.modules) {
+      const module = Modifications.modules[m];
+      for (var bp in module.blueprints) {
+        expect(Modifications.blueprints[bp]).toBeDefined('Missing ' + bp + ' for ' + m);
+        for (var g in module.blueprints[bp]) {
+          const grade = module.blueprints[bp][g];
+          expect(Modifications.blueprints[bp].grades[grade]).toBeDefined('Missing ' + bp + ' grade ' + grade + ' for ' + m);
+        }
+      }
+    }
   });
 
   it('has valid specials', function() {