diff --git a/README.md b/README.md
index 4e30314..439ac4c 100644
--- a/README.md
+++ b/README.md
@@ -93,7 +93,7 @@ Located in `build/reports/tests-execution/mermaid/*.txt`.
 
 ```
 gantt
-dateFormat YYYY-MM-DD\THH\:mm\:ss\.SSSZ
+dateFormat YYYY-MM-DDTHH:mm:ss.SSSZZ
 axisFormat %H:%M:%S.%L
 section Test1Spec
 test 2 - 120 ms :active, 2022-11-08T20:46:17.854+0100, 2022-11-08T20:46:17.974+0100
@@ -104,7 +104,7 @@ rendered: ([info](https://github.blog/2022-02-14-include-diagrams-markdown-files
 
 ```mermaid
 gantt
-dateFormat YYYY-MM-DD\THH\:mm\:ss\.SSSZ
+dateFormat YYYY-MM-DDTHH:mm:ss.SSSZZ
 axisFormat %H:%M:%S.%L
 section Test1Spec
 test 2 - 120 ms :active, 2022-11-08T20:46:17.854+0100, 2022-11-08T20:46:17.974+0100
@@ -227,7 +227,9 @@ Gradle can generate reports in JUnit XML format. But such reports cannot be used
 
 ## Unreleased
 
-- nothing
+### Changed
+
+- Use `dateFormat` compatible with Mermaid 9.4.2
 
 ## 0.2.1 (07 March 2023)
 
diff --git a/src/main/kotlin/io/github/platan/tests_execution_chart/reporters/mermaid/TestExecutionMermaidDiagramFormatter.kt b/src/main/kotlin/io/github/platan/tests_execution_chart/reporters/mermaid/TestExecutionMermaidDiagramFormatter.kt
index 60fe95d..81d62fe 100644
--- a/src/main/kotlin/io/github/platan/tests_execution_chart/reporters/mermaid/TestExecutionMermaidDiagramFormatter.kt
+++ b/src/main/kotlin/io/github/platan/tests_execution_chart/reporters/mermaid/TestExecutionMermaidDiagramFormatter.kt
@@ -14,7 +14,7 @@ class TestExecutionMermaidDiagramFormatter {
             val testNameWithDuration = "${it.testName} - ${it.endTime.minus(it.startTime)} ms"
             diagramBuilder.add(it.className!!, testNameWithDuration, types[it.resultType], it.startTime, it.endTime)
         }
-        val diagram = diagramBuilder.build("YYYY-MM-DD\\THH\\:mm\\:ss\\.SSSZ", "%H:%M:%S.%L")
+        val diagram = diagramBuilder.build("YYYY-MM-DDTHH:mm:ss.SSSZZ", "%H:%M:%S.%L")
         return MermaidGanttDiagramFormatter().format(diagram, "yyyy-MM-dd'T'HH:mm:ss.SSSZ")
     }
 }