diff --git a/src/Services/ParameterService.ts b/src/Services/ParameterService.ts
index 85e69c0f27fab6e8012e737f4658af6e9c5af7dd..8430a176fadf1f364ca0cecaa390091590c222d8 100644
--- a/src/Services/ParameterService.ts
+++ b/src/Services/ParameterService.ts
@@ -307,7 +307,11 @@ const updateExtraData = async (parameters: DefaultExtraDataDTO[]): Promise<void>
 
   if (ids.includes(extraDataIDs.minLowPrev)) {
     if (ids.includes(extraDataIDs.minModPrev) && ids.includes(extraDataIDs.minIntPrev)) {
-      await updatePercentage(parameters, total);
+      if (ids.length === 3) {
+        await updatePercentage(parameters, total);
+      } else {
+        throw new Error('Too many parameters sent');
+      }
     } else {
       throw new Error('Missing parameter for update');
     }
diff --git a/swagger.yaml b/swagger.yaml
index ebfacb136c61c2c2e41c54be04be58b14549b510..b35eb72985d92234e01907306359a4cb30dd607b 100644
--- a/swagger.yaml
+++ b/swagger.yaml
@@ -104,7 +104,7 @@ paths:
     put:
       tags:
         - Parameters
-      summary: Update a certain parameter
+      summary: Update a certain parameter. The array should contain exactly one item, unless the parameters to be updated are a trio, in which case all three parameters should be included.
       requestBody:
         content:
           application/json: