diff --git a/jacodb-approximations/src/main/kotlin/org/jacodb/approximation/Approximations.kt b/jacodb-approximations/src/main/kotlin/org/jacodb/approximation/Approximations.kt
index d661b04a4..eb2280752 100644
--- a/jacodb-approximations/src/main/kotlin/org/jacodb/approximation/Approximations.kt
+++ b/jacodb-approximations/src/main/kotlin/org/jacodb/approximation/Approximations.kt
@@ -178,13 +178,13 @@ private class ApproximationIndexer(
         val approximationClassName = classNode.name.className.toApproximationName()
 
         // Ensure that each approximation has one and only one
-        require(originalClassName !in originalToApproximation) {
+        require(originalToApproximation.getOrDefault(originalClassName, approximationClassName) == approximationClassName) {
             "An error occurred during approximations indexing: you tried to add `$approximationClassName` " +
                     "as an approximation for `$originalClassName`, but the target class is already " +
                     "associated with approximation `${originalToApproximation[originalClassName]}`. " +
                     "Only bijection between classes is allowed."
         }
-        require(approximationClassName !in approximationToOriginal) {
+        require(approximationToOriginal.getOrDefault(approximationClassName, originalClassName) == originalClassName) {
             "An error occurred during approximations indexing: you tried to add `$approximationClassName` " +
                     "as an approximation for `$originalClassName`, but this approximation is already used for " +
                     "`${approximationToOriginal[approximationClassName]}`. " +
diff --git a/jacodb-core/src/main/kotlin/org/jacodb/impl/storage/PersistentByteCodeLocation.kt b/jacodb-core/src/main/kotlin/org/jacodb/impl/storage/PersistentByteCodeLocation.kt
index b1f947bc0..2f5e41332 100644
--- a/jacodb-core/src/main/kotlin/org/jacodb/impl/storage/PersistentByteCodeLocation.kt
+++ b/jacodb-core/src/main/kotlin/org/jacodb/impl/storage/PersistentByteCodeLocation.kt
@@ -87,10 +87,9 @@ class PersistentByteCodeLocation(
         }
     }
 
-    override val jcLocation: JcByteCodeLocation?
-        get() {
-            return cachedLocation ?: data.toJcLocation()
-        }
+    override val jcLocation: JcByteCodeLocation? by lazy(LazyThreadSafetyMode.PUBLICATION) {
+        cachedLocation ?: data.toJcLocation()
+    }
 
     override val path: String
         get() = data.path
@@ -138,4 +137,3 @@ class PersistentByteCodeLocation(
         }
     }
 }
-