diff --git a/src/coreclr/vm/zapsig.cpp b/src/coreclr/vm/zapsig.cpp
index bbbab9a51c84d4..dfd447f94eaaf6 100644
--- a/src/coreclr/vm/zapsig.cpp
+++ b/src/coreclr/vm/zapsig.cpp
@@ -1350,6 +1350,9 @@ BOOL ZapSig::EncodeMethod(
         else
         {
             Instantiation inst = pMethod->GetMethodInstantiation();
+
+            pSigBuilder->AppendData(inst.GetNumArgs());
+
             for (DWORD i = 0; i < inst.GetNumArgs(); i++)
             {
                 TypeHandle t = inst[i];