a.diff

diff --git a/core/src/main/java/org/jruby/Ruby.java b/core/src/main/java/org/jruby/Ruby.java
index d21b780e1a..d530c60e84 100644
--- a/core/src/main/java/org/jruby/Ruby.java
+++ b/core/src/main/java/org/jruby/Ruby.java
@@ -2924,10 +2924,16 @@ public final class Ruby implements Constantizable {
                 Ruby runtime = context.runtime;
                 RubyBinding binding = RubyBinding.newBinding(runtime, context.currentBinding());
 
+                RubyString eventNameString = runtime.newString(eventName.equals("c_return") ?
+                        "c-return" :
+                        eventName.equals("c_call") ?
+                                "c-call" :
+                                eventName);
+
                 context.preTrace();
                 try {
                     traceFunc.call(context, new IRubyObject[]{
-                            runtime.newString(eventName), // event name
+                            eventNameString,
                             runtime.newString(file), // filename
                             runtime.newFixnum(line), // line numbers should be 1-based
                             name != null ? runtime.newSymbol(name) : runtime.getNil(),