diff --git a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
index 8a45ec983ce..896348d86f4 100644
--- a/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
+++ b/compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/expression/FirOptInUsageBaseChecker.kt
@@ -206,8 +206,10 @@ object FirOptInUsageBaseChecker {
                     Experimentality.Severity.WARNING -> FirErrors.OPT_IN_USAGE to "should"
                     Experimentality.Severity.ERROR -> FirErrors.OPT_IN_USAGE_ERROR to "must"
                 }
-                val reportedMessage = message?.takeIf { it.isNotBlank() } ?: "This declaration is experimental and its usage $verb be marked"
-                reporter.reportOn(element.source, diagnostic, annotationClassId.asSingleFqName(), reportedMessage, context)
+                val fqName = annotationClassId.asSingleFqName()
+                val reportedMessage = message?.takeIf { it.isNotBlank() }
+                    ?: OptInNames.buildDefaultDiagnosticMessage(OptInNames.buildMessagePrefix(verb), fqName)
+                reporter.reportOn(element.source, diagnostic, fqName, reportedMessage, context)
             }
         }
     }
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExperimentalUsageChecker.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExperimentalUsageChecker.kt
index d4588f04d7c..5a5855d581c 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExperimentalUsageChecker.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExperimentalUsageChecker.kt
@@ -118,18 +118,18 @@ class ExperimentalUsageChecker(project: Project) : CallChecker {
         private val WARNING_LEVEL = Name.identifier("WARNING")
         private val ERROR_LEVEL = Name.identifier("ERROR")
 
-        internal fun getDefaultDiagnosticMessage(prefix: String) = fun(fqName: FqName): String {
-            return "$prefix with '@${fqName.asString()}' or '@OptIn(${fqName.asString()}::class)'"
+        internal fun getDefaultDiagnosticMessage(prefix: String): (FqName) -> String = { fqName: FqName ->
+            OptInNames.buildDefaultDiagnosticMessage(prefix, fqName)
         }
 
         private val USAGE_DIAGNOSTICS = ExperimentalityDiagnostics(
             warning = ExperimentalityDiagnostic2(
                 Errors.OPT_IN_USAGE,
-                getDefaultDiagnosticMessage("This declaration is experimental and its usage should be marked")
+                getDefaultDiagnosticMessage(OptInNames.buildMessagePrefix("should"))
             ),
             error = ExperimentalityDiagnostic2(
                 Errors.OPT_IN_USAGE_ERROR,
-                getDefaultDiagnosticMessage("This declaration is experimental and its usage must be marked")
+                getDefaultDiagnosticMessage(OptInNames.buildMessagePrefix("must"))
             ),
             futureError = ExperimentalityDiagnostic2(
                 Errors.OPT_IN_USAGE_FUTURE_ERROR,
diff --git a/compiler/testData/cli/jvm/optInEmptyMessage.out b/compiler/testData/cli/jvm/optInEmptyMessage.out
index d9ea1ee1b33..168a6ceb01f 100644
--- a/compiler/testData/cli/jvm/optInEmptyMessage.out
+++ b/compiler/testData/cli/jvm/optInEmptyMessage.out
@@ -1,4 +1,4 @@
-compiler/testData/cli/jvm/optInEmptyMessage.kt:8:5: error: this declaration is experimental and its usage must be marked with '@EmptyMarker' or '@OptIn(EmptyMarker::class)'
+compiler/testData/cli/jvm/optInEmptyMessage.kt:8:5: error: this declaration needs OptIn. Its usage must be marked with '@EmptyMarker' or '@OptIn(EmptyMarker::class)'
     foo()
     ^
 COMPILATION_ERROR
diff --git a/compiler/testData/cli/jvm/optInEmptyMessageFir.args b/compiler/testData/cli/jvm/optInEmptyMessageFir.args
index 360bd46a8dd..f9f8c27de5f 100644
--- a/compiler/testData/cli/jvm/optInEmptyMessageFir.args
+++ b/compiler/testData/cli/jvm/optInEmptyMessageFir.args
@@ -1,4 +1,4 @@
-$TESTDATA_DIR$/optInEmptyMessage.kt
+$TESTDATA_DIR$/optInEmptyMessageFir.kt
 -d
 $TEMP_DIR$
 -opt-in=kotlin.RequiresOptIn
diff --git a/compiler/testData/cli/jvm/optInEmptyMessageFir.out b/compiler/testData/cli/jvm/optInEmptyMessageFir.out
index 09585a6ac28..a3a60f4d360 100644
--- a/compiler/testData/cli/jvm/optInEmptyMessageFir.out
+++ b/compiler/testData/cli/jvm/optInEmptyMessageFir.out
@@ -1,7 +1,7 @@
 warning: ATTENTION!
  This build uses in-dev FIR:
   -Xuse-fir
-compiler/testData/cli/jvm/optInEmptyMessage.kt:8:5: error: this declaration is experimental and its usage must be marked
+compiler/testData/cli/jvm/optInEmptyMessage.kt:8:5: error: this declaration needs OptIn. Its usage must be marked with '@EmptyMarker' or '@OptIn(EmptyMarker::class)'
     foo()
     ^
 COMPILATION_ERROR
diff --git a/compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.out b/compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.out
index e1c6fceaf63..d96ed48710c 100644
--- a/compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.out
+++ b/compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.out
@@ -1,17 +1,17 @@
 warning: language version 1.4 is deprecated and its support will be removed in a future version of Kotlin
-compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:2:13: warning: this declaration is experimental and its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
+compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:2:13: warning: this declaration needs OptIn. Its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
 fun test(p: ULong) {
             ^
-compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:3:12: warning: this declaration is experimental and its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
+compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:3:12: warning: this declaration needs OptIn. Its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
     val z: ULong = p
            ^
-compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:3:20: warning: this declaration is experimental and its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
+compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:3:20: warning: this declaration needs OptIn. Its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
     val z: ULong = p
                    ^
-compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:4:5: warning: this declaration is experimental and its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
+compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:4:5: warning: this declaration needs OptIn. Its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
     z.inv()
     ^
-compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:4:7: warning: this declaration is experimental and its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
+compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker2.kt:4:7: warning: this declaration needs OptIn. Its usage should be marked with '@kotlin.ExperimentalUnsignedTypes' or '@OptIn(kotlin.ExperimentalUnsignedTypes::class)'
     z.inv()
       ^
 OK
diff --git a/core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/OptInNames.kt b/core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/OptInNames.kt
index 47769f356eb..2ef0955a402 100644
--- a/core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/OptInNames.kt
+++ b/core/compiler.common/src/org/jetbrains/kotlin/resolve/checkers/OptInNames.kt
@@ -38,4 +38,11 @@ object OptInNames {
     )
     @Suppress("unused")
     val USE_EXPERIMENTAL_FQ_NAMES = OPT_IN_FQ_NAMES
+
+    fun buildDefaultDiagnosticMessage(prefix: String, fqName: FqName): String {
+        return "$prefix with '@${fqName.asString()}' or '@OptIn(${fqName.asString()}::class)'"
+    }
+
+    fun buildMessagePrefix(verb: String): String =
+        "This declaration needs OptIn. Its usage $verb be marked"
 }
\ No newline at end of file