diff --git a/markdown/build.gradle.kts b/markdown/build.gradle.kts
index 9b00118..b5e7527 100644
--- a/markdown/build.gradle.kts
+++ b/markdown/build.gradle.kts
@@ -51,6 +51,7 @@ dependencies {
     testImplementation("com.nhaarman.mockitokotlin2:mockito-kotlin:2.2.0")
     testImplementation("com.flextrade.jfixture:jfixture:2.7.2")
     testImplementation("io.github.classgraph:classgraph:4.8.95")
+    testImplementation("com.google.jimfs:jimfs:1.1")
 
     testImplementation("org.spekframework.spek2:spek-dsl-jvm:2.0.15")
     testRuntimeOnly("org.spekframework.spek2:spek-runner-junit5:2.0.15")
diff --git a/markdown/src/main/kotlin/com/appmattus/markdown/filter/SinglePathFilter.kt b/markdown/src/main/kotlin/com/appmattus/markdown/filter/SinglePathFilter.kt
index 1577035..1028ed4 100644
--- a/markdown/src/main/kotlin/com/appmattus/markdown/filter/SinglePathFilter.kt
+++ b/markdown/src/main/kotlin/com/appmattus/markdown/filter/SinglePathFilter.kt
@@ -33,7 +33,7 @@ class SinglePathFilter(
     }
 
     override fun matches(path: Path): Boolean {
-        val relativePath = Paths.get(".").resolve(root.relativize(path).normalize())
+        val relativePath = path.fileSystem.getPath(".").resolve(root.relativize(path).normalize())
         return matcher.matches(relativePath)
     }
 }
diff --git a/markdown/src/main/kotlin/com/appmattus/markdown/processing/RuleProcessor.kt b/markdown/src/main/kotlin/com/appmattus/markdown/processing/RuleProcessor.kt
index 612c76b..a7c11c6 100644
--- a/markdown/src/main/kotlin/com/appmattus/markdown/processing/RuleProcessor.kt
+++ b/markdown/src/main/kotlin/com/appmattus/markdown/processing/RuleProcessor.kt
@@ -121,7 +121,9 @@ class RuleProcessor(private val rootDir: Path, private val reportsDir: Path) {
 
         Files.walkFileTree(this, object : SimpleFileVisitor<Path>() {
             override fun preVisitDirectory(dir: Path, attrs: BasicFileAttributes): FileVisitResult {
-                return if (dir.fileName.toString() == "build" || dir.fileName.toString().startsWith(".")) {
+                /* The fileName component is null if the dir is the root of the filesystem. */
+                return if (dir.fileName != null &&
+                        (dir.fileName.toString() == "build" || dir.fileName.toString().startsWith("."))) {
                     FileVisitResult.SKIP_SUBTREE
                 } else {
                     FileVisitResult.CONTINUE
diff --git a/markdown/src/test/kotlin/com/appmattus/markdown/plugin/MarkdownLintPluginTest.kt b/markdown/src/test/kotlin/com/appmattus/markdown/plugin/MarkdownLintPluginTest.kt
index 31fbea3..e5eb47e 100644
--- a/markdown/src/test/kotlin/com/appmattus/markdown/plugin/MarkdownLintPluginTest.kt
+++ b/markdown/src/test/kotlin/com/appmattus/markdown/plugin/MarkdownLintPluginTest.kt
@@ -481,6 +481,13 @@ private fun InputStream.toFile(file: File) {
 }
 
 private fun GradleRunner.withJaCoCo(): GradleRunner {
-    javaClass.classLoader.getResourceAsStream("testkit-gradle.properties").toFile(File(projectDir, "gradle.properties"))
+    /*
+     * When running under Windows, the forked Gradle VM will linger briefly and keep
+     * some files open, which interferes with Gradle snapshotting. As long as some
+     * OS runs JaCoCo coverage for statistics, it is good enough.
+     */
+    if (!System.getProperty("os.name").toLowerCase().contains("win")) {
+        javaClass.classLoader.getResourceAsStream("testkit-gradle.properties").toFile(File(projectDir, "gradle.properties"))
+    }
     return this
 }
diff --git a/markdown/src/test/kotlin/com/appmattus/markdown/processing/RuleProcessorTest.kt b/markdown/src/test/kotlin/com/appmattus/markdown/processing/RuleProcessorTest.kt
index 2bf5b1d..2a6883b 100644
--- a/markdown/src/test/kotlin/com/appmattus/markdown/processing/RuleProcessorTest.kt
+++ b/markdown/src/test/kotlin/com/appmattus/markdown/processing/RuleProcessorTest.kt
@@ -2,8 +2,8 @@ package com.appmattus.markdown.processing
 
 import com.appmattus.markdown.dsl.Config
 import com.appmattus.markdown.plugin.MarkdownLint
+import com.google.common.jimfs.Jimfs
 import org.assertj.core.api.Assertions.assertThat
-import org.junit.rules.TemporaryFolder
 import org.spekframework.spek2.Spek
 import org.spekframework.spek2.style.gherkin.Feature
 import java.io.ByteArrayOutputStream
@@ -19,18 +19,20 @@ object RuleProcessorTest : Spek({
     }
 
     Feature("RuleProcessor") {
-        val temporaryFolder by memoized {
-            TemporaryFolder().apply {
-                create()
-            }
+        val fileSystem by memoized {
+            Jimfs.newFileSystem()
         }
 
         val rootDir by memoized {
-            temporaryFolder.newFolder("rootDir").toPath()
+            fileSystem.getPath("rootDir").also {
+                Files.createDirectories(it)
+            }
         }
 
         val reportsDir by memoized {
-            temporaryFolder.newFolder("reportsDir").toPath()
+            fileSystem.getPath("reportsDir").also {
+                Files.createDirectories(it)
+            }
         }
 
         val slash = Regex.escape(File.separator)
diff --git a/markdown/src/test/kotlin/com/appmattus/markdown/rules/Files.kt b/markdown/src/test/kotlin/com/appmattus/markdown/rules/Files.kt
index a429fad..9a746e6 100644
--- a/markdown/src/test/kotlin/com/appmattus/markdown/rules/Files.kt
+++ b/markdown/src/test/kotlin/com/appmattus/markdown/rules/Files.kt
@@ -35,7 +35,7 @@ val allFiles = listOf(
     "header_duplicate_content_different_nesting.md",
     "header_duplicate_content_no_different_nesting.md",
     "header_multiple_toplevel.md",
-    "header_mutliple_h1_no_toplevel.md",
+    "header_multiple_h1_no_toplevel.md",
     "header_trailing_punctuation.md",
     "header_trailing_punctuation_customized.md",
     "headers_bad.md",
diff --git a/markdown/src/test/resources/header_mutliple_h1_no_toplevel.md b/markdown/src/test/resources/header_multiple_h1_no_toplevel.md
similarity index 100%
rename from markdown/src/test/resources/header_mutliple_h1_no_toplevel.md
rename to markdown/src/test/resources/header_multiple_h1_no_toplevel.md
diff --git a/settings.gradle.kts b/settings.gradle.kts
index c7dd1af..17d84f9 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -1,3 +1,5 @@
+rootProject.name = "markdown-lint"
+
 include(
     "markdown"
 )