diff --git a/src/script_opt/ZAM/Stmt.cc b/src/script_opt/ZAM/Stmt.cc
index 4753717d94..d353827b68 100644
--- a/src/script_opt/ZAM/Stmt.cc
+++ b/src/script_opt/ZAM/Stmt.cc
@@ -591,7 +591,7 @@ const ZAMStmt ZAMCompiler::TypeSwitch(const SwitchStmt* sw, const NameExpr* v, c
     int ntypes = type_map->size();
     auto aux = new ZInstAux(ntypes);
 
-    for ( auto i = 0; i < type_map->size(); ++i ) {
+    for ( size_t i = 0; i < type_map->size(); ++i ) {
         auto& tm = (*type_map)[i];
         auto id_i = tm.first;
         auto id_case = tm.second;
diff --git a/src/script_opt/ZAM/ZOp.h b/src/script_opt/ZAM/ZOp.h
index 72ae94ddd3..09e44f145d 100644
--- a/src/script_opt/ZAM/ZOp.h
+++ b/src/script_opt/ZAM/ZOp.h
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <string>
+#include <unordered_map>
 
 namespace zeek::detail {