diff --git a/common/main/aistruct.h b/common/main/aistruct.h
index 422940027..b6cc8facb 100644
--- a/common/main/aistruct.h
+++ b/common/main/aistruct.h
@@ -174,17 +174,12 @@ enum class ai_mode : uint8_t
 #endif
 
 //  Constants defining meaning of flags in ai_state
-#define MAX_AI_FLAGS    5          // This MUST cause word (4 bytes) alignment in ai_static, allowing for one byte mode
+#define MAX_AI_FLAGS    4          // This MUST cause word (4 bytes) alignment in ai_static, allowing for one byte mode
 
 #define CURRENT_GUN     flags[0]    // This is the last gun the object fired from
 #define CURRENT_STATE   flags[1]    // current behavioral state
 #define GOAL_STATE      flags[2]    // goal state
 #define PATH_DIR        flags[3]    // direction traveling path, 1 = forward, -1 = backward, other = error!
-#if defined(DXX_BUILD_DESCENT_I)
-#define	SUBMODE			flags[4]			//	submode, eg AISM_HIDING if mode == AIM_HIDE
-#elif defined(DXX_BUILD_DESCENT_II)
-#define SUB_FLAGS       flags[4]    // bit 0: Set -> Robot's current gun in different segment than robot's center.
-#endif
 
 // This is the stuff that is permanent for an AI object.
 #ifdef dsx
@@ -221,6 +216,11 @@ struct ai_static : public prohibit_void_ptr<ai_static>
 {
 	ai_behavior behavior = static_cast<ai_behavior>(0);               //
 	std::array<sbyte, MAX_AI_FLAGS> flags{};    // various flags, meaning defined by constants
+#if defined(DXX_BUILD_DESCENT_I)
+	int8_t SUBMODE;					//	submode, eg AISM_HIDING if mode == AIM_HIDE
+#elif defined(DXX_BUILD_DESCENT_II)
+	int8_t SUB_FLAGS;				// bit 0: Set -> Robot's current gun in different segment than robot's center.
+#endif
 	int8_t GOALSIDE;				// for guys who open doors, this is the side they are going after.
 	int8_t CLOAKED{};					// Cloaked now.
 	int8_t SKIP_AI_COUNT{};			// Skip AI this frame, but decrement in do_ai_frame.
@@ -247,7 +247,7 @@ struct ai_static : public prohibit_void_ptr<ai_static>
 struct ai_static_rw
 {
 	ubyte   behavior;               //
-	int8_t  flags[MAX_AI_FLAGS + 6];    // various flags, meaning defined by constants
+	int8_t  flags[MAX_AI_FLAGS + 7];    // various flags, meaning defined by constants
 	short   hide_segment;           // Segment to go to for hiding.
 	short   hide_index;             // Index in Path_seg_points
 	short   path_length;            // Length of hide path.
diff --git a/similar/main/gamesave.cpp b/similar/main/gamesave.cpp
index df587f5ee..d3a326cec 100644
--- a/similar/main/gamesave.cpp
+++ b/similar/main/gamesave.cpp
@@ -484,7 +484,12 @@ static void read_object(const vmobjptr_t obj,PHYSFS_File *f,int version)
 				i = PHYSFSX_readByte(f);
 
 			std::array<int8_t, 11> ai_info_flags{};
-			PHYSFS_read(f, &ai_info_flags[5], 1, 6);
+			PHYSFS_read(f, &ai_info_flags[4], 1, 7);
+#if defined(DXX_BUILD_DESCENT_I)
+			obj->ctype.ai_info.SUBMODE = ai_info_flags[4];
+#elif defined(DXX_BUILD_DESCENT_II)
+			obj->ctype.ai_info.SUB_FLAGS = ai_info_flags[4];
+#endif
 			obj->ctype.ai_info.GOALSIDE = ai_info_flags[5];
 			obj->ctype.ai_info.CLOAKED = ai_info_flags[6];
 			obj->ctype.ai_info.SKIP_AI_COUNT = ai_info_flags[7];
@@ -746,12 +751,17 @@ static void write_object(const object &obj, short version, PHYSFS_File *f)
 				PHYSFSX_writeU8(f, i);
 
 			std::array<int8_t, 11> ai_info_flags{};
+#if defined(DXX_BUILD_DESCENT_I)
+			ai_info_flags[4] = obj.ctype.ai_info.SUBMODE;
+#elif defined(DXX_BUILD_DESCENT_II)
+			ai_info_flags[4] = obj.ctype.ai_info.SUB_FLAGS;
+#endif
 			ai_info_flags[5] = obj.ctype.ai_info.GOALSIDE;
 			ai_info_flags[6] = obj.ctype.ai_info.CLOAKED;
 			ai_info_flags[7] = obj.ctype.ai_info.SKIP_AI_COUNT;
 			ai_info_flags[8] = obj.ctype.ai_info.REMOTE_OWNER;
 			ai_info_flags[9] = obj.ctype.ai_info.REMOTE_SLOT_NUM;
-			PHYSFS_write(f, &ai_info_flags[5], 1, 6);
+			PHYSFS_write(f, &ai_info_flags[4], 1, 7);
 			PHYSFS_writeSLE16(f, obj.ctype.ai_info.hide_segment);
 			PHYSFS_writeSLE16(f, obj.ctype.ai_info.hide_index);
 			PHYSFS_writeSLE16(f, obj.ctype.ai_info.path_length);
diff --git a/similar/main/multi.cpp b/similar/main/multi.cpp
index 36742e1da..3ef3008b0 100644
--- a/similar/main/multi.cpp
+++ b/similar/main/multi.cpp
@@ -5996,6 +5996,11 @@ void multi_object_to_object_rw(const object &obj, object_rw *obj_rw)
 			obj_rw->ctype.ai_info.behavior               = static_cast<uint8_t>(obj.ctype.ai_info.behavior);
 			for (i = 0; i < MAX_AI_FLAGS; i++)
 				obj_rw->ctype.ai_info.flags[i]       = obj.ctype.ai_info.flags[i]; 
+#if defined(DXX_BUILD_DESCENT_I)
+			obj_rw->ctype.ai_info.flags[4] = obj.ctype.ai_info.SUBMODE;
+#elif defined(DXX_BUILD_DESCENT_II)
+			obj_rw->ctype.ai_info.flags[4] = obj.ctype.ai_info.SUB_FLAGS;
+#endif
 			obj_rw->ctype.ai_info.flags[5] = obj.ctype.ai_info.GOALSIDE;
 			obj_rw->ctype.ai_info.flags[6] = obj.ctype.ai_info.CLOAKED;
 			obj_rw->ctype.ai_info.flags[7] = obj.ctype.ai_info.SKIP_AI_COUNT;
@@ -6183,6 +6188,11 @@ void multi_object_rw_to_object(const object_rw *const obj_rw, object &obj)
 			obj.ctype.ai_info.behavior               = static_cast<ai_behavior>(obj_rw->ctype.ai_info.behavior);
 			for (i = 0; i < MAX_AI_FLAGS; i++)
 				obj.ctype.ai_info.flags[i]       = obj_rw->ctype.ai_info.flags[i]; 
+#if defined(DXX_BUILD_DESCENT_I)
+			obj.ctype.ai_info.SUBMODE = obj_rw->ctype.ai_info.flags[4];
+#elif defined(DXX_BUILD_DESCENT_II)
+			obj.ctype.ai_info.SUB_FLAGS = obj_rw->ctype.ai_info.flags[4];
+#endif
 			obj.ctype.ai_info.GOALSIDE = obj_rw->ctype.ai_info.flags[5];
 			obj.ctype.ai_info.CLOAKED = obj_rw->ctype.ai_info.flags[6];
 			obj.ctype.ai_info.SKIP_AI_COUNT = obj_rw->ctype.ai_info.flags[7];
diff --git a/similar/main/state.cpp b/similar/main/state.cpp
index a5360a014..26a0077e7 100644
--- a/similar/main/state.cpp
+++ b/similar/main/state.cpp
@@ -401,6 +401,11 @@ static void state_object_to_object_rw(const object &obj, object_rw *const obj_rw
 			obj_rw->ctype.ai_info.behavior               = static_cast<uint8_t>(obj.ctype.ai_info.behavior);
 			for (i = 0; i < MAX_AI_FLAGS; i++)
 				obj_rw->ctype.ai_info.flags[i]       = obj.ctype.ai_info.flags[i]; 
+#if defined(DXX_BUILD_DESCENT_I)
+			obj_rw->ctype.ai_info.flags[4] = obj.ctype.ai_info.SUBMODE;
+#elif defined(DXX_BUILD_DESCENT_II)
+			obj_rw->ctype.ai_info.flags[4] = obj.ctype.ai_info.SUB_FLAGS;
+#endif
 			obj_rw->ctype.ai_info.flags[5] = obj.ctype.ai_info.GOALSIDE;
 			obj_rw->ctype.ai_info.flags[6] = obj.ctype.ai_info.CLOAKED;
 			obj_rw->ctype.ai_info.flags[7] = obj.ctype.ai_info.SKIP_AI_COUNT;
@@ -600,6 +605,11 @@ static void state_object_rw_to_object(const object_rw *const obj_rw, object &obj
 			obj.ctype.ai_info.behavior               = static_cast<ai_behavior>(obj_rw->ctype.ai_info.behavior);
 			for (i = 0; i < MAX_AI_FLAGS; i++)
 				obj.ctype.ai_info.flags[i]       = obj_rw->ctype.ai_info.flags[i]; 
+#if defined(DXX_BUILD_DESCENT_I)
+			obj.ctype.ai_info.SUBMODE = obj_rw->ctype.ai_info.flags[4];
+#elif defined(DXX_BUILD_DESCENT_II)
+			obj.ctype.ai_info.SUB_FLAGS = obj_rw->ctype.ai_info.flags[4];
+#endif
 			obj.ctype.ai_info.GOALSIDE = obj_rw->ctype.ai_info.flags[5];
 			obj.ctype.ai_info.CLOAKED = obj_rw->ctype.ai_info.flags[6];
 			obj.ctype.ai_info.SKIP_AI_COUNT = obj_rw->ctype.ai_info.flags[7];