diff --git a/src/game/game_gui.cpp b/src/game/game_gui.cpp
--- a/src/game/game_gui.cpp
+++ b/src/game/game_gui.cpp
@@ -199,10 +199,18 @@ struct GSConfigWindow : public Window {
 					TextColour colour;
 					uint idx = 0;
 					if (config_item.description.empty()) {
-						str = STR_JUST_STRING1;
+						if (Game::GetInstance() == nullptr && config_item.random_deviation != 0) {
+							str = STR_AI_SETTINGS_JUST_DEVIATION;
+						} else {
+							str = STR_JUST_STRING1;
+						}
 						colour = TC_ORANGE;
 					} else {
-						str = STR_AI_SETTINGS_SETTING;
+						if (Game::GetInstance() == nullptr && config_item.random_deviation != 0) {
+							str = STR_AI_SETTINGS_SETTING_DEVIATION;
+						} else {
+							str = STR_AI_SETTINGS_SETTING;
+						}
 						colour = TC_LIGHT_BLUE;
 						SetDParamStr(idx++, config_item.description);
 					}
@@ -216,13 +224,36 @@ struct GSConfigWindow : public Window {
 						} else {
 							DrawArrowButtons(br.left, y + button_y_offset, COLOUR_YELLOW, (this->clicked_button == i) ? 1 + (this->clicked_increase != rtl) : 0, editable && current_value > config_item.min_value, editable && current_value < config_item.max_value);
 						}
-						auto config_iterator = config_item.labels.find(current_value);
-						if (config_iterator != config_item.labels.end()) {
-							SetDParam(idx++, STR_JUST_RAW_STRING);
-							SetDParamStr(idx++, config_iterator->second);
+
+						if (Game::GetInstance() != nullptr || config_item.random_deviation == 0) {
+							auto config_iterator = config_item.labels.find(current_value);
+							if (config_iterator != config_item.labels.end()) {
+								SetDParam(idx++, STR_JUST_RAW_STRING);
+								SetDParamStr(idx++, config_iterator->second);
+							} else {
+								SetDParam(idx++, STR_JUST_INT);
+								SetDParam(idx++, current_value);
+							}
 						} else {
-							SetDParam(idx++, STR_JUST_INT);
-							SetDParam(idx++, current_value);
+							int min_deviated = std::max(config_item.min_value, current_value - config_item.random_deviation);
+							auto config_iterator = config_item.labels.find(min_deviated);
+							if (config_iterator != config_item.labels.end()) {
+								SetDParam(idx++, STR_JUST_RAW_STRING);
+								SetDParamStr(idx++, config_iterator->second);
+							} else {
+								SetDParam(idx++, STR_JUST_INT);
+								SetDParam(idx++, min_deviated);
+							}
+
+							int max_deviated = std::min(config_item.max_value, current_value + config_item.random_deviation);
+							config_iterator = config_item.labels.find(max_deviated);
+							if (config_iterator != config_item.labels.end()) {
+								SetDParam(idx++, STR_JUST_RAW_STRING);
+								SetDParamStr(idx++, config_iterator->second);
+							} else {
+								SetDParam(idx++, STR_JUST_INT);
+								SetDParam(idx++, max_deviated);
+							}
 						}
 					}
 
diff --git a/src/lang/english.txt b/src/lang/english.txt
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -4835,6 +4835,8 @@ STR_AI_SETTINGS_CAPTION_GAMESCRIPT      
 STR_AI_SETTINGS_CLOSE                                           :{BLACK}Close
 STR_AI_SETTINGS_RESET                                           :{BLACK}Reset
 STR_AI_SETTINGS_SETTING                                         :{RAW_STRING}: {ORANGE}{STRING1}
+STR_AI_SETTINGS_SETTING_DEVIATION                               :{RAW_STRING}: {ORANGE}[{STRING1}, {STRING1}]
+STR_AI_SETTINGS_JUST_DEVIATION                                  :[{STRING1}, {STRING1}]
 
 
 # Textfile window
diff --git a/src/script/api/script_info_docs.hpp b/src/script/api/script_info_docs.hpp
--- a/src/script/api/script_info_docs.hpp
+++ b/src/script/api/script_info_docs.hpp
@@ -239,6 +239,7 @@ public:
 	 *    [user_configured_value - random_deviation, user_configured_value + random_deviation] (inclusive).
 	 *    random_deviation sign is ignored and the value is clamped in the range [0, MAX(int32_t)] (inclusive).
 	 *    The randomisation will happen just before the Script start.
+	 *    Not allowed if the CONFIG_BOOLEAN flag is set, otherwise optional.
 	 *  - step_size The increase/decrease of the value every time the user
 	 *    clicks one of the up/down arrow buttons. Optional, default is 1.
 	 *  - flags Bitmask of some flags, see ScriptConfigFlags. Required.
diff --git a/src/script/script_gui.cpp b/src/script/script_gui.cpp
--- a/src/script/script_gui.cpp
+++ b/src/script/script_gui.cpp
@@ -379,10 +379,18 @@ struct ScriptSettingsWindow : public Win
 			TextColour colour;
 			uint idx = 0;
 			if (config_item.description.empty()) {
-				str = STR_JUST_STRING1;
+				if (this->slot != OWNER_DEITY && !Company::IsValidID(this->slot) && config_item.random_deviation != 0) {
+					str = STR_AI_SETTINGS_JUST_DEVIATION;
+				} else {
+					str = STR_JUST_STRING1;
+				}
 				colour = TC_ORANGE;
 			} else {
-				str = STR_AI_SETTINGS_SETTING;
+				if (this->slot != OWNER_DEITY && !Company::IsValidID(this->slot) && config_item.random_deviation != 0) {
+					str = STR_AI_SETTINGS_SETTING_DEVIATION;
+				} else {
+					str = STR_AI_SETTINGS_SETTING;
+				}
 				colour = TC_LIGHT_BLUE;
 				SetDParamStr(idx++, config_item.description);
 			}
@@ -397,13 +405,35 @@ struct ScriptSettingsWindow : public Win
 					DrawArrowButtons(br.left, y + button_y_offset, COLOUR_YELLOW, (this->clicked_button == i) ? 1 + (this->clicked_increase != rtl) : 0, editable && current_value > config_item.min_value, editable && current_value < config_item.max_value);
 				}
 
-				auto config_iterator = config_item.labels.find(current_value);
-				if (config_iterator != config_item.labels.end()) {
-					SetDParam(idx++, STR_JUST_RAW_STRING);
-					SetDParamStr(idx++, config_iterator->second);
+				if (this->slot == OWNER_DEITY || Company::IsValidID(this->slot) || config_item.random_deviation == 0) {
+					auto config_iterator = config_item.labels.find(current_value);
+					if (config_iterator != config_item.labels.end()) {
+						SetDParam(idx++, STR_JUST_RAW_STRING);
+						SetDParamStr(idx++, config_iterator->second);
+					} else {
+						SetDParam(idx++, STR_JUST_INT);
+						SetDParam(idx++, current_value);
+					}
 				} else {
-					SetDParam(idx++, STR_JUST_INT);
-					SetDParam(idx++, current_value);
+					int min_deviated = std::max(config_item.min_value, current_value - config_item.random_deviation);
+					auto config_iterator = config_item.labels.find(min_deviated);
+					if (config_iterator != config_item.labels.end()) {
+						SetDParam(idx++, STR_JUST_RAW_STRING);
+						SetDParamStr(idx++, config_iterator->second);
+					} else {
+						SetDParam(idx++, STR_JUST_INT);
+						SetDParam(idx++, min_deviated);
+					}
+
+					int max_deviated = std::min(config_item.max_value, current_value + config_item.random_deviation);
+					config_iterator = config_item.labels.find(max_deviated);
+					if (config_iterator != config_item.labels.end()) {
+						SetDParam(idx++, STR_JUST_RAW_STRING);
+						SetDParamStr(idx++, config_iterator->second);
+					} else {
+						SetDParam(idx++, STR_JUST_INT);
+						SetDParam(idx++, max_deviated);
+					}
 				}
 			}
 
diff --git a/src/script/script_info.cpp b/src/script/script_info.cpp
--- a/src/script/script_info.cpp
+++ b/src/script/script_info.cpp
@@ -162,6 +162,13 @@ SQInteger ScriptInfo::AddSetting(HSQUIRR
 	}
 	sq_pop(vm, 1);
 
+	/* Don't allow both random_deviation and SCRIPTCONFIG_BOOLEAN to
+	 * be set for the same config item. */
+	if ((items & 0x200) != 0 && (config.flags & SCRIPTCONFIG_BOOLEAN) != 0) {
+		this->engine->ThrowError("setting both random_deviation and CONFIG_BOOLEAN is not allowed");
+		return SQ_ERROR;
+	}
+
 	/* Reset the bit for random_deviation as it's optional. */
 	items &= ~0x200;