diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
index 0128c0a48dab..55d655d7a5f2 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginLoadingResult.java
@@ -8,6 +8,7 @@ import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.ContainerUtilRt;
 import com.intellij.util.text.VersionComparatorUtil;
 import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -166,6 +167,12 @@ final class PluginLoadingResult {
     }
   }
 
+  @Contract(pure = true)
+  boolean contains(@NotNull IdeaPluginDescriptorImpl descriptor) {
+    PluginId pluginId = descriptor.getPluginId();
+    return (pluginId != null && plugins.containsKey(pluginId));
+  }
+
   private boolean isCompatible(@NotNull IdeaPluginDescriptorImpl descriptor) {
     return PluginManagerCore.isIncompatible(productBuildNumber, descriptor.getSinceBuild(), descriptor.getUntilBuild()) == null;
   }
diff --git a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
index e5668045e9c5..c0bf3621a81d 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
+++ b/platform/core-impl/src/com/intellij/ide/plugins/PluginManagerCore.java
@@ -1163,7 +1163,8 @@ public final class PluginManagerCore {
     PluginLoadingResult result = context.parentContext.result;
     for (Future<IdeaPluginDescriptorImpl> task : tasks) {
       IdeaPluginDescriptorImpl descriptor = task.get();
-      if (descriptor != null) {
+      // plugins added via property shouldn't be overridden to avoid plugin root detection issues when running external plugin tests
+      if (descriptor != null && !result.contains(descriptor)) {
         descriptor.setUseCoreClassLoader();
         result.add(descriptor, context.parentContext);
       }