diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
index a761c14fff3..d7db9248ce2 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
@@ -648,9 +648,9 @@ public interface Errors {
     DiagnosticFactory2<KtNamedDeclaration, MemberDescriptor,
             Map<Incompatible, Collection<MemberDescriptor>>> ACTUAL_WITHOUT_EXPECT =
             DiagnosticFactory2.create(ERROR, INCOMPATIBLE_DECLARATION);
-    DiagnosticFactory2<KtNamedDeclaration, DeclarationDescriptor, Collection<String>> AMBIGUOUS_ACTUALS =
+    DiagnosticFactory2<KtNamedDeclaration, DeclarationDescriptor, Collection<ModuleDescriptor>> AMBIGUOUS_ACTUALS =
             DiagnosticFactory2.create(ERROR, INCOMPATIBLE_DECLARATION);
-    DiagnosticFactory2<KtNamedDeclaration, DeclarationDescriptor, Collection<String>> AMBIGUOUS_EXPECTS =
+    DiagnosticFactory2<KtNamedDeclaration, DeclarationDescriptor, Collection<ModuleDescriptor>> AMBIGUOUS_EXPECTS =
             DiagnosticFactory2.create(ERROR, INCOMPATIBLE_DECLARATION);
 
     DiagnosticFactory2<KtNamedDeclaration, ClassDescriptor,
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
index d9ec4596688..997375bea7d 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
@@ -288,9 +288,9 @@ public class DefaultErrorMessages {
         MAP.put(ACTUAL_WITHOUT_EXPECT, "{0} has no corresponding expected declaration{1}", CAPITALIZED_DECLARATION_NAME_WITH_KIND_AND_PLATFORM,
                 PlatformIncompatibilityDiagnosticRenderer.TEXT);
         MAP.put(AMBIGUOUS_ACTUALS, "{0} has several compatible actual declarations in modules {1}", CAPITALIZED_DECLARATION_NAME_WITH_KIND_AND_PLATFORM, commaSeparated(
-                STRING));
+                MODULE));
         MAP.put(AMBIGUOUS_EXPECTS, "{0} has several compatible expect declarations in modules {1}", CAPITALIZED_DECLARATION_NAME_WITH_KIND_AND_PLATFORM, commaSeparated(
-                STRING));
+                MODULE));
 
         MAP.put(NO_ACTUAL_CLASS_MEMBER_FOR_EXPECTED_CLASS, "Actual class ''{0}'' has no corresponding members for expected class members:{1}",
                 NAME, IncompatibleExpectedActualClassScopesRenderer.TEXT);
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt
index dcc3624ec19..f425e0eb9e9 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/Renderers.kt
@@ -82,11 +82,16 @@ object Renderers {
     @JvmField
     val MODULE_WITH_PLATFORM = Renderer<ModuleDescriptor> { module ->
         val platform = module.platform
-        val moduleName = module.moduleInfo?.unwrapPlatform()?.displayedName ?: ""
+        val moduleName = MODULE.render(module)
         val platformNameIfAny = if (platform == null || platform.isCommon()) "" else " for " + platform.single().platformName
 
         moduleName + platformNameIfAny
     }
+
+    @JvmField
+    val MODULE = Renderer<ModuleDescriptor> { module ->
+        module.moduleInfo?.unwrapPlatform()?.displayedName ?: module.name.asString()
+    }
     
     @JvmField
     val VISIBILITY = Renderer<Visibility> {
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
index 5f7f5e7938f..a19621689c0 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt
@@ -144,8 +144,8 @@ class ExpectedActualDeclarationChecker(
                 reportOn,
                 descriptor,
                 atLeastWeaklyCompatibleActuals
-                    .map { DescriptorUtils.getContainingSourceFile(it).let { it.name ?: it.toString() } }
-                    .sorted()
+                    .map { it.module }
+                    .sortedBy { it.name.asString() }
             ))
         }
     }
@@ -305,8 +305,8 @@ class ExpectedActualDeclarationChecker(
             }
             .map { (_, members) -> members }
             .flatten()
-            .map { DescriptorUtils.getContainingSourceFile(it).let { it.name ?: it.toString() } }
-            .sorted()
+            .map { it.module }
+            .sortedBy { it.name.asString() }
             .toList()
 
         if (filesWithAtLeastWeaklyCompatibleExpects.size > 1) {
diff --git a/compiler/testData/multiplatform/incompatibleCallables/output.txt b/compiler/testData/multiplatform/incompatibleCallables/output.txt
index 59beb40b009..e3a6f2305b4 100644
--- a/compiler/testData/multiplatform/incompatibleCallables/output.txt
+++ b/compiler/testData/multiplatform/incompatibleCallables/output.txt
@@ -5,73 +5,73 @@ Output:
 -- JVM --
 Exit code: COMPILATION_ERROR
 Output:
-compiler/testData/multiplatform/incompatibleCallables/common.kt:1:12: error: expected function 'f1' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:1:12: error: expected function 'f1' has no actual declaration in module <main>
 The following declaration is incompatible because return type is different:
     public actual fun f1(): String
 
 expect fun f1()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:5:14: error: expected function 'f3' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:5:14: error: expected function 'f3' has no actual declaration in module <main>
 The following declaration is incompatible because parameter types are different:
     public actual fun f3(name: Double): Unit
 
 expect fun f3(name: String)
              ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:6:24: error: expected function 'f3ext' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:6:24: error: expected function 'f3ext' has no actual declaration in module <main>
 The following declaration is incompatible because parameter types are different:
     public actual fun Double.f3ext(): Unit
 
 expect fun String.f3ext()
                        ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:8:14: error: expected function 'f4' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:8:14: error: expected function 'f4' has no actual declaration in module <main>
 The following declaration is incompatible because parameter shapes are different (extension vs non-extension):
     public actual fun String.f4(): Unit
 
 expect fun f4(name: String)
              ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:10:12: error: expected function 'f5' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:10:12: error: expected function 'f5' has no actual declaration in module <main>
 The following declaration is incompatible because parameter shapes are different (extension vs non-extension):
     public actual fun f5(name: String): Unit
 
 expect fun String.f5()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:12:14: error: expected function 'f6' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:12:14: error: expected function 'f6' has no actual declaration in module <main>
 The following declaration is incompatible because number of value parameters is different:
     public actual fun f6(p2: Int): Unit
 
 expect fun f6(p1: String, p2: Int)
              ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:14:12: error: expected function 'f7' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:14:12: error: expected function 'f7' has no actual declaration in module <main>
 The following declaration is incompatible because number of type parameters is different:
     public actual fun <K, V> f7(): Unit
 
 expect fun <T> f7()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:19:12: error: expected function 'f11' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:19:12: error: expected function 'f11' has no actual declaration in module <main>
 The following declaration is incompatible because upper bounds of type parameters are different:
     public actual fun <T : Annotation> f11(): Unit
 
 expect fun <T : Number> f11()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:20:12: error: expected function 'f12' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:20:12: error: expected function 'f12' has no actual declaration in module <main>
 The following declaration is incompatible because upper bounds of type parameters are different:
     public actual fun <U : MutableList<out String>> f12(): Unit
 
 expect fun <U : MutableList<String>> f12()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:21:12: error: expected function 'f13' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:21:12: error: expected function 'f13' has no actual declaration in module <main>
 The following declaration is incompatible because upper bounds of type parameters are different:
     public actual fun <A, B : Comparable<B>> f13(): Unit
 
 expect fun <A, B : Comparable<A>> f13()
            ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:32:15: error: expected function 'f21' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:32:15: error: expected function 'f21' has no actual declaration in module <main>
 The following declaration is incompatible because parameter types are different:
     public actual fun f21(c: Unit.() -> Unit): Unit
 
 expect fun f21(c: suspend Unit.() -> Unit)
               ^
-compiler/testData/multiplatform/incompatibleCallables/common.kt:33:15: error: expected function 'f22' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleCallables/common.kt:33:15: error: expected function 'f22' has no actual declaration in module <main>
 The following declaration is incompatible because parameter types are different:
     public actual fun f22(c: suspend Unit.() -> Unit): Unit
 
diff --git a/compiler/testData/multiplatform/incompatibleClasses/output.txt b/compiler/testData/multiplatform/incompatibleClasses/output.txt
index ddc84732ccd..4e7690428d6 100644
--- a/compiler/testData/multiplatform/incompatibleClasses/output.txt
+++ b/compiler/testData/multiplatform/incompatibleClasses/output.txt
@@ -5,19 +5,19 @@ Output:
 -- JVM --
 Exit code: COMPILATION_ERROR
 Output:
-compiler/testData/multiplatform/incompatibleClasses/common.kt:14:16: error: expected class 'C1' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleClasses/common.kt:14:16: error: expected class 'C1' has no actual declaration in module <main>
 The following declaration is incompatible because number of type parameters is different:
     public final actual class C1<A, Extra>
 
 expect class C1<A>
                ^
-compiler/testData/multiplatform/incompatibleClasses/common.kt:16:16: error: expected class 'C3' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleClasses/common.kt:16:16: error: expected class 'C3' has no actual declaration in module <main>
 The following declaration is incompatible because upper bounds of type parameters are different:
     public final actual class C3<D, E : D?>
 
 expect class C3<D, E : D>
                ^
-compiler/testData/multiplatform/incompatibleClasses/common.kt:18:16: error: expected class 'C4' has no actual declaration in module
+compiler/testData/multiplatform/incompatibleClasses/common.kt:18:16: error: expected class 'C4' has no actual declaration in module <main>
 The following declaration is incompatible because upper bounds of type parameters are different:
     public actual typealias C4<F> = C4Impl<F>
 
diff --git a/compiler/testData/multiplatform/missingOverload/output.txt b/compiler/testData/multiplatform/missingOverload/output.txt
index d645a28807b..77a5fe18462 100644
--- a/compiler/testData/multiplatform/missingOverload/output.txt
+++ b/compiler/testData/multiplatform/missingOverload/output.txt
@@ -5,7 +5,7 @@ Output:
 -- JVM --
 Exit code: COMPILATION_ERROR
 Output:
-compiler/testData/multiplatform/missingOverload/common.kt:7:13: error: expected function 'g' has no actual declaration in module
+compiler/testData/multiplatform/missingOverload/common.kt:7:13: error: expected function 'g' has no actual declaration in module <main>
 The following declaration is incompatible because parameter types are different:
     public actual fun g(a: Any): Unit
 
diff --git a/compiler/testData/multiplatform/optionalExpectationIncorrectUse/output.txt b/compiler/testData/multiplatform/optionalExpectationIncorrectUse/output.txt
index ae14699df26..31294e4e405 100644
--- a/compiler/testData/multiplatform/optionalExpectationIncorrectUse/output.txt
+++ b/compiler/testData/multiplatform/optionalExpectationIncorrectUse/output.txt
@@ -26,7 +26,7 @@ fun useInSignature(a: A) = a.toString()
 compiler/testData/multiplatform/optionalExpectationIncorrectUse/common.kt:9:1: error: this annotation is not applicable to target 'class'
 @OptionalExpectation
 ^
-compiler/testData/multiplatform/optionalExpectationIncorrectUse/common.kt:10:14: error: expected class 'NotAnAnnotationClass' has no actual declaration in module
+compiler/testData/multiplatform/optionalExpectationIncorrectUse/common.kt:10:14: error: expected class 'NotAnAnnotationClass' has no actual declaration in module <main>
 expect class NotAnAnnotationClass
              ^
 compiler/testData/multiplatform/optionalExpectationIncorrectUse/common.kt:12:1: error: '@OptionalExpectation' can only be used on an expected annotation class
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/top/top.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/top/top.kt
index 86b95aaf804..221b2f07557 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/top/top.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/diamondDuplicateActuals/top/top.kt
@@ -1,5 +1,5 @@
 package sample
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom.kt, left.kt")!>A<!> {
-    fun <!AMBIGUOUS_ACTUALS("Function 'foo'", "bottom.kt, left.kt")!>foo<!>(): Int
+expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom, left")!>A<!> {
+    fun <!AMBIGUOUS_ACTUALS("Function 'foo'", "bottom, left")!>foo<!>(): Int
 }
\ No newline at end of file
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsExplicit/top/top.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsExplicit/top/top.kt
index 1bc425490ae..b6529b5b63b 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsExplicit/top/top.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsExplicit/top/top.kt
@@ -1,3 +1,3 @@
 package foo
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom.kt, middle.kt")!>A<!>
\ No newline at end of file
+expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom, middle")!>A<!>
\ No newline at end of file
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsImplicit/top/top.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsImplicit/top/top.kt
index 01bdb4dc0f8..e4fecfc1a1e 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsImplicit/top/top.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsImplicit/top/top.kt
@@ -1,6 +1,6 @@
 package foo
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'ActualInMiddleCompatibleInBottom'", "bottom.kt, middle.kt")!>ActualInMiddleCompatibleInBottom<!>
-expect class <!AMBIGUOUS_ACTUALS("Class 'CompatibleInMiddleActualInBottom'", "bottom.kt, middle.kt")!>CompatibleInMiddleActualInBottom<!>
+expect class <!AMBIGUOUS_ACTUALS("Class 'ActualInMiddleCompatibleInBottom'", "bottom, middle")!>ActualInMiddleCompatibleInBottom<!>
+expect class <!AMBIGUOUS_ACTUALS("Class 'CompatibleInMiddleActualInBottom'", "bottom, middle")!>CompatibleInMiddleActualInBottom<!>
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'CompatibleInMiddleAndBottom'", "bottom.kt, middle.kt")!>CompatibleInMiddleAndBottom<!>
\ No newline at end of file
+expect class <!AMBIGUOUS_ACTUALS("Class 'CompatibleInMiddleAndBottom'", "bottom, middle")!>CompatibleInMiddleAndBottom<!>
\ No newline at end of file
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsOneWeaklyIncompatible/top/top.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsOneWeaklyIncompatible/top/top.kt
index 1bc425490ae..b6529b5b63b 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsOneWeaklyIncompatible/top/top.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateActualsOneWeaklyIncompatible/top/top.kt
@@ -1,3 +1,3 @@
 package foo
 
-expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom.kt, middle.kt")!>A<!>
\ No newline at end of file
+expect class <!AMBIGUOUS_ACTUALS("Class 'A'", "bottom, middle")!>A<!>
\ No newline at end of file
diff --git a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateExpectsExplicit/bottom/bottom.kt b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateExpectsExplicit/bottom/bottom.kt
index 14e2680967d..c73c470e0d0 100644
--- a/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateExpectsExplicit/bottom/bottom.kt
+++ b/idea/testData/multiModuleHighlighting/hierarchicalExpectActualMatching/duplicateExpectsExplicit/bottom/bottom.kt
@@ -1 +1 @@
-actual class <!AMBIGUOUS_EXPECTS("Actual class 'A'", "left.kt, right.kt")!>A<!>
\ No newline at end of file
+actual class <!AMBIGUOUS_EXPECTS("Actual class 'A'", "left, right")!>A<!>
\ No newline at end of file