diff --git a/Sources/LowEnergyCommandParameter.swift b/Sources/LowEnergyCommandParameter.swift
index 03cc8803a..8ea2b98a3 100644
--- a/Sources/LowEnergyCommandParameter.swift
+++ b/Sources/LowEnergyCommandParameter.swift
@@ -26,6 +26,8 @@ public extension LowEnergyCommand {
         
         public init(data: LowEnergyAdvertisingData, length: UInt8) {
             
+            precondition(length <= 31, "LE Advertising Data can only be 31 octets")
+            
             self.length = length
             self.data = data
         }
@@ -156,6 +158,8 @@ public extension LowEnergyCommand {
         
         public init(data: LowEnergyScanData, length: UInt8) {
             
+            precondition(length <= 31, "LE Scan Response Data can only be 31 octets")
+            
             self.length = length
             self.data = data
         }