diff --git a/shared/src/main/scala/io/kaitai/struct/ClassTypeProvider.scala b/shared/src/main/scala/io/kaitai/struct/ClassTypeProvider.scala
index 9875efaa8..11dc24e2f 100644
--- a/shared/src/main/scala/io/kaitai/struct/ClassTypeProvider.scala
+++ b/shared/src/main/scala/io/kaitai/struct/ClassTypeProvider.scala
@@ -155,8 +155,12 @@ class ClassTypeProvider(classSpecs: ClassSpecs, var topClass: ClassSpec) extends
           case Some(upClass) => resolveTypeName(upClass, typeName)
           case None =>
             classSpecs.get(typeName) match {
-              case Some(spec) => spec
-              case None =>
+              // We should use that spec if it is imported in our file (which is represented
+              // by our top-level class). If `topClass` imports `classSpec`, we could try to
+              // resolve type in it
+              // TODO: if type is defined in spec, we could add a suggestion to error to add missing import
+              case Some(spec) if (topClass.imports.contains(spec)) => spec
+              case _ =>
                 throw new TypeNotFoundInHierarchyError(typeName, nowClass)
             }
         }
diff --git a/shared/src/main/scala/io/kaitai/struct/format/ClassSpec.scala b/shared/src/main/scala/io/kaitai/struct/format/ClassSpec.scala
index 6a3cb0135..d2282f3ad 100644
--- a/shared/src/main/scala/io/kaitai/struct/format/ClassSpec.scala
+++ b/shared/src/main/scala/io/kaitai/struct/format/ClassSpec.scala
@@ -81,6 +81,16 @@ case class ClassSpec(
 
   var seqSize: Sized = NotCalculatedSized
 
+  /**
+    * The list of top-level type specifications which is imported to the file,
+    * which top-level type is represented by this class.
+    *
+    * This collection filled only for top-level classes (for which [[upClass]] is `None`).
+    *
+    * This collection is filled by the [[io.kaitai.struct.precompile.LoadImports]] pass.
+    */
+  var imports = mutable.ListBuffer[ClassSpec]()
+
   def toDataType: DataType = {
     val cut = CalcUserType(name, None)
     cut.classSpec = Some(this)
diff --git a/shared/src/main/scala/io/kaitai/struct/precompile/LoadImports.scala b/shared/src/main/scala/io/kaitai/struct/precompile/LoadImports.scala
index d25bfeb9b..16f7ae6b3 100644
--- a/shared/src/main/scala/io/kaitai/struct/precompile/LoadImports.scala
+++ b/shared/src/main/scala/io/kaitai/struct/precompile/LoadImports.scala
@@ -32,7 +32,7 @@ class LoadImports(specs: ClassSpecs) {
         loadImport(
           name,
           curClass.meta.path ++ List("imports", idx.toString),
-          Some(curClass.fileNameAsStr),
+          curClass,
           workDir
         )
       }).map((x) => x.flatten)
@@ -44,9 +44,10 @@ class LoadImports(specs: ClassSpecs) {
     Future.sequence(List(thisMetaFuture, nestedFuture)).map((x) => x.flatten)
   }
 
-  private def loadImport(name: String, path: List[String], inFile: Option[String], workDir: ImportPath): Future[List[ClassSpec]] = {
+  private def loadImport(name: String, path: List[String], curClass: ClassSpec, workDir: ImportPath): Future[List[ClassSpec]] = {
     Log.importOps.info(() => s".. LoadImports: loadImport($name, workDir = $workDir)")
 
+    val inFile = Some(curClass.fileNameAsStr)
     val impPath = ImportPath.fromString(name)
     val fullPath = ImportPath.add(workDir, impPath)
 
@@ -63,8 +64,9 @@ class LoadImports(specs: ClassSpecs) {
         s".. LoadImports: loadImport($name, workDir = $workDir), got spec=$specNameAsStr"
       })
       optSpec match {
-        case Some(spec) =>
-          val specName = spec.name.head
+        case Some(importedSpec) =>
+          curClass.imports += importedSpec
+          val specName = importedSpec.name.head
           // Check if spec name does not match file name. If it doesn't match,
           // it is probably already a serious error.
           if (name != specName)
@@ -88,12 +90,12 @@ class LoadImports(specs: ClassSpecs) {
           val isNewSpec = specs.synchronized {
             val isNew = !specs.contains(specName)
             if (isNew) {
-              specs(specName) = spec
+              specs(specName) = importedSpec
             }
             isNew
           }
           if (isNewSpec) {
-            processClass(spec, ImportPath.updateWorkDir(workDir, impPath))
+            processClass(importedSpec, ImportPath.updateWorkDir(workDir, impPath))
           } else {
             Log.importOps.warn(() => s"... we have that already, ignoring")
             Future { List() }
diff --git a/shared/src/main/scala/io/kaitai/struct/precompile/ResolveTypes.scala b/shared/src/main/scala/io/kaitai/struct/precompile/ResolveTypes.scala
index fe003195f..ae69ffe83 100644
--- a/shared/src/main/scala/io/kaitai/struct/precompile/ResolveTypes.scala
+++ b/shared/src/main/scala/io/kaitai/struct/precompile/ResolveTypes.scala
@@ -10,8 +10,11 @@ import io.kaitai.struct.problems._
 /**
   * A collection of methods that resolves user types and enum types, i.e.
   * converts names into ClassSpec / EnumSpec references.
+  *
+  * This step runs for each top-level [[format.ClassSpec]].
   */
 class ResolveTypes(specs: ClassSpecs, topClass: ClassSpec, opaqueTypes: Boolean) extends PrecompileStep {
+  /** Resolves references to types and enums in `topClass` and all its nested types. */
   override def run(): Iterable[CompilationProblem] =
     topClass.mapRec(resolveUserTypes).map(problem => problem.localizedInType(topClass))
 
@@ -44,6 +47,16 @@ class ResolveTypes(specs: ClassSpecs, topClass: ClassSpec, opaqueTypes: Boolean)
   private def resolveUserTypeForMember(curClass: ClassSpec, attr: MemberSpec): Iterable[CompilationProblem] =
     resolveUserType(curClass, attr.dataType, attr.path)
 
+  /**
+    * Resolves any references to typee or enum in `dataType` used in `curClass` to
+    * a type definition, or returns [[TypeNotFoundErr]] or [[EnumNotFoundErr]] error.
+    *
+    * @param curClass Class that contains member
+    * @param dataType Definition of an attribute type which references to a type or enum need to be resolved
+    * @param path A path to the attribute in KSY where the error should be reported if reference is unknown
+    *
+    * @returns [[TypeNotFoundErr]] and/or [[EnumNotFoundErr]] error (several in case of `switch-on` type).
+    */
   private def resolveUserType(curClass: ClassSpec, dataType: DataType, path: List[String]): Iterable[CompilationProblem] = {
     dataType match {
       case ut: UserType =>