diff --git a/src/main/java/org/antlr/intellij/plugin/parsing/RunANTLROnGrammarFile.java b/src/main/java/org/antlr/intellij/plugin/parsing/RunANTLROnGrammarFile.java
index f53abce9..16d377e1 100644
--- a/src/main/java/org/antlr/intellij/plugin/parsing/RunANTLROnGrammarFile.java
+++ b/src/main/java/org/antlr/intellij/plugin/parsing/RunANTLROnGrammarFile.java
@@ -6,6 +6,7 @@
 import com.intellij.notification.NotificationType;
 import com.intellij.notification.Notifications;
 import com.intellij.openapi.application.ApplicationManager;
+import com.intellij.openapi.application.ReadAction;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.openapi.progress.Task;
@@ -75,7 +76,7 @@ public void run(@NotNull ProgressIndicator indicator) {
 		ANTLRv4GrammarProperties grammarProperties = getGrammarProperties(project, grammarFile);
 		boolean autogen = grammarProperties.shouldAutoGenerateParser();
 		if ( forceGeneration || (autogen && isGrammarStale(grammarProperties)) ) {
-			antlr(grammarFile);
+			ReadAction.run(() -> antlr(grammarFile));
 		}
 		else {
 			ANTLRv4PluginController controller = ANTLRv4PluginController.getInstance(project);