diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 196982084..3f4f11813 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -1360,7 +1360,13 @@ bool is_polymorphic_type_assignable(CheckerContext *c, Type *poly, Type *source,
 		if (source->kind == Type_Map) {
 			bool key   = is_polymorphic_type_assignable(c, poly->Map.key, source->Map.key, true, modify_type);
 			bool value = is_polymorphic_type_assignable(c, poly->Map.value, source->Map.value, true, modify_type);
-			return key || value;
+			if (key || value) {
+				poly->Map.entry_type = nullptr;
+				poly->Map.internal_type = nullptr;
+				poly->Map.lookup_result_type = nullptr;
+				init_map_internal_types(poly);
+				return true;
+			}
 		}
 		return false;
 		
diff --git a/src/check_type.cpp b/src/check_type.cpp
index c024e0842..2ffe04342 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -2211,7 +2211,6 @@ void init_map_internal_types(Type *type) {
 	GB_ASSERT(type->kind == Type_Map);
 	init_map_entry_type(type);
 	if (type->Map.internal_type != nullptr) return;
-	if (type->Map.generated_struct_type != nullptr) return;
 
 	Type *key   = type->Map.key;
 	Type *value = type->Map.value;
@@ -2239,7 +2238,6 @@ void init_map_internal_types(Type *type) {
 	generated_struct_type->Struct.fields = fields;
 	type_set_offsets(generated_struct_type);
 	
-	type->Map.generated_struct_type = generated_struct_type;
 	type->Map.internal_type         = generated_struct_type;
 	type->Map.lookup_result_type    = make_optional_ok_type(value);
 }
diff --git a/src/checker.cpp b/src/checker.cpp
index e30dea6e1..5bdc5b010 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -1922,7 +1922,7 @@ void add_type_info_type_internal(CheckerContext *c, Type *t) {
 		init_map_internal_types(bt);
 		add_type_info_type_internal(c, bt->Map.key);
 		add_type_info_type_internal(c, bt->Map.value);
-		add_type_info_type_internal(c, bt->Map.generated_struct_type);
+		add_type_info_type_internal(c, bt->Map.internal_type);
 		break;
 
 	case Type_Tuple:
@@ -2144,7 +2144,7 @@ void add_min_dep_type_info(Checker *c, Type *t) {
 		init_map_internal_types(bt);
 		add_min_dep_type_info(c, bt->Map.key);
 		add_min_dep_type_info(c, bt->Map.value);
-		add_min_dep_type_info(c, bt->Map.generated_struct_type);
+		add_min_dep_type_info(c, bt->Map.internal_type);
 		break;
 
 	case Type_Tuple:
diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp
index 8bee5c9e5..e563fabb7 100644
--- a/src/llvm_backend.cpp
+++ b/src/llvm_backend.cpp
@@ -521,7 +521,6 @@ lbValue lb_gen_map_header_table_internal(lbProcedure *p, Type *map_type) {
 	i64 value_offset = type_offset_of(map_type->Map.entry_type, 3);
 	i64 value_size   = type_size_of  (map_type->Map.value);
 
-
 	Type *key_type = map_type->Map.key;
 	Type *val_type = map_type->Map.value;
 	gb_unused(val_type);
diff --git a/src/llvm_backend_type.cpp b/src/llvm_backend_type.cpp
index d424fa5b2..61955d934 100644
--- a/src/llvm_backend_type.cpp
+++ b/src/llvm_backend_type.cpp
@@ -787,7 +787,7 @@ void lb_setup_type_info_data(lbProcedure *p) { // NOTE(bill): Setup type_info da
 			tag = lb_const_ptr_cast(m, variant_ptr, t_type_info_map_ptr);
 			init_map_internal_types(t);
 			
-			lbValue gst = lb_type_info(m, t->Map.generated_struct_type);
+			lbValue gst = lb_type_info(m, t->Map.internal_type);
 
 			LLVMValueRef vals[5] = {
 				lb_type_info(m, t->Map.key).value,
diff --git a/src/llvm_backend_utility.cpp b/src/llvm_backend_utility.cpp
index 14592f29a..a54171b51 100644
--- a/src/llvm_backend_utility.cpp
+++ b/src/llvm_backend_utility.cpp
@@ -1130,7 +1130,7 @@ lbValue lb_emit_struct_ev(lbProcedure *p, lbValue s, i32 index) {
 	case Type_Map:
 		{
 			init_map_internal_types(t);
-			Type *gst = t->Map.generated_struct_type;
+			Type *gst = t->Map.internal_type;
 			switch (index) {
 			case 0: result_type = get_struct_field_type(gst, 0); break;
 			case 1: result_type = get_struct_field_type(gst, 1); break;
diff --git a/src/types.cpp b/src/types.cpp
index 321f42aa0..fec324bf4 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -227,7 +227,6 @@ struct TypeProc {
 		Type *key;                                        \
 		Type *value;                                      \
 		Type *entry_type;                                 \
-		Type *generated_struct_type;                      \
 		Type *internal_type;                              \
 		Type *lookup_result_type;                         \
 	})                                                        \