diff --git a/src/company_base.h b/src/company_base.h
--- a/src/company_base.h
+++ b/src/company_base.h
@@ -83,13 +83,13 @@ struct Company : PoolItem<Company, Compa
 	uint16 *num_engines; ///< caches the number of engines of each type the company owns (no need to save this)
 
 	inline bool IsValid() const { return this->name_1 != 0; }
+
+	static inline bool IsValidID(CompanyID company)
+	{
+		return company < MAX_COMPANIES && (uint)company < Company::GetPoolSize() && Company::Get(company)->IsValid();
+	}
 };
 
-static inline bool IsValidCompanyID(CompanyID company)
-{
-	return company < MAX_COMPANIES && (uint)company < Company::GetPoolSize() && Company::Get(company)->IsValid();
-}
-
 #define FOR_ALL_COMPANIES_FROM(d, start) for (d = Company::Get(start); d != NULL; d = (d->index + 1U < Company::GetPoolSize()) ? Company::Get(d->index + 1U) : NULL) if (d->IsValid())
 #define FOR_ALL_COMPANIES(d) FOR_ALL_COMPANIES_FROM(d, 0)