diff --git a/src/ai/ai_config.cpp b/src/ai/ai_config.cpp
index 20e913c2e9..a782814786 100644
--- a/src/ai/ai_config.cpp
+++ b/src/ai/ai_config.cpp
@@ -35,6 +35,15 @@ ScriptConfigItem _start_date_config = {
 	false
 };
 
+AIConfig::AIConfig(const AIConfig *config) : ScriptConfig(config)
+{
+	/* Override start_date as per AIConfig::AddRandomDeviation().
+	 * This is necessary because the ScriptConfig constructor will instead call
+	 * ScriptConfig::AddRandomDeviation(). */
+	int start_date = config->GetSetting("start_date");
+	this->SetSetting("start_date", start_date != 0 ? max(1, this->GetSetting("start_date")) : 0);
+}
+
 /* static */ AIConfig *AIConfig::GetConfig(CompanyID company, ScriptSettingSource source)
 {
 	AIConfig **config;
diff --git a/src/ai/ai_config.hpp b/src/ai/ai_config.hpp
index 600ae1af93..30c6f84bbd 100644
--- a/src/ai/ai_config.hpp
+++ b/src/ai/ai_config.hpp
@@ -26,9 +26,7 @@ public:
 		ScriptConfig()
 	{}
 
-	AIConfig(const AIConfig *config) :
-		ScriptConfig(config)
-	{}
+	AIConfig(const AIConfig *config);
 
 	class AIInfo *GetInfo() const;