diff --git a/jps/model-api/src/org/jetbrains/jps/util/JpsPathUtil.java b/jps/model-api/src/org/jetbrains/jps/util/JpsPathUtil.java
index fa425f1187e1..b5b25dabe1be 100644
--- a/jps/model-api/src/org/jetbrains/jps/util/JpsPathUtil.java
+++ b/jps/model-api/src/org/jetbrains/jps/util/JpsPathUtil.java
@@ -99,6 +99,12 @@ public class JpsPathUtil {
 
   public static @NotNull String getDefaultProjectName(@NotNull Path projectDir) {
     Path parent = projectDir.getParent();
-    return parent != null ? parent.getFileName().toString() : UNNAMED_PROJECT;
+    if (parent != null) {
+      Path name = parent.getFileName();  // `null` when parent is a Windows disk root
+      return name != null ? name.toString() : parent.toString();
+    }
+    else {
+      return UNNAMED_PROJECT;
+    }
   }
 }
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