diff --git a/src/Java.Interop/Java.Interop/JniEnvironment.Types.cs b/src/Java.Interop/Java.Interop/JniEnvironment.Types.cs
index af0ca4ff1..a50f0b19a 100644
--- a/src/Java.Interop/Java.Interop/JniEnvironment.Types.cs
+++ b/src/Java.Interop/Java.Interop/JniEnvironment.Types.cs
@@ -200,9 +200,15 @@ public static void RegisterNatives (JniObjectReference type, JniNativeMethodRegi
 
 			public static void RegisterNatives (JniObjectReference type, JniNativeMethodRegistration [] methods, int numMethods)
 			{
+				if ((numMethods < 0) ||
+						(numMethods > (methods?.Length ?? 0))) {
+					throw new ArgumentOutOfRangeException (nameof (numMethods), numMethods,
+							$"`numMethods` must be between 0 and `methods.Length` ({methods?.Length ?? 0})!");
+				}
 #if DEBUG && NETCOREAPP
-				foreach (var m in methods) {
-					if (m.Marshaler.GetType ().GenericTypeArguments.Length != 0) {
+				for (int i = 0; methods != null && i < numMethods; ++i) {
+					var m   = methods [i];
+					if (m.Marshaler != null && m.Marshaler.GetType ().GenericTypeArguments.Length != 0) {
 						var method  = m.Marshaler.Method;
 						Debug.WriteLine ($"JNIEnv::RegisterNatives() given a generic delegate type `{m.Marshaler.GetType()}`.  .NET Core doesn't like this.");
 						Debug.WriteLine ($"  Java: {m.Name}{m.Signature}");