diff --git a/include/QF/progs.h b/include/QF/progs.h
index 3cd6a5c6c..c393be5a5 100644
--- a/include/QF/progs.h
+++ b/include/QF/progs.h
@@ -1857,9 +1857,8 @@ struct progs_s {
 	/// \name debugging
 	///@{
 	struct prdeb_resources_s *pr_debug_resources;
-	void      (*debug_handler) (prdebug_t event, void *data);
+	void      (*debug_handler) (prdebug_t event, void *param, void *data);
 	void       *debug_data;
-	const char *error_string;
 	pr_type_t  *watch;
 	int         wp_conditional;
 	pr_type_t   wp_val;
diff --git a/libs/gamecode/pr_exec.c b/libs/gamecode/pr_exec.c
index 43681da79..425ec5f64 100644
--- a/libs/gamecode/pr_exec.c
+++ b/libs/gamecode/pr_exec.c
@@ -55,7 +55,7 @@
 VISIBLE void
 PR_RunError (progs_t * pr, const char *error, ...)
 {
-	dstring_t  *string = dstring_new ();
+	dstring_t  *string = dstring_new ();//FIXME leaks when debugging
 	va_list     argptr;
 
 	va_start (argptr, error);
@@ -63,8 +63,7 @@ PR_RunError (progs_t * pr, const char *error, ...)
 	va_end (argptr);
 
 	if (pr->debug_handler) {
-		pr->error_string = string->str;
-		pr->debug_handler (prd_runerror, pr->debug_data);
+		pr->debug_handler (prd_runerror, string->str, pr->debug_data);
 		// not expected to return, but if so, behave as if there was no handler
 	}
 
@@ -486,7 +485,7 @@ PR_ExecuteProgram (progs_t *pr, func_t fnum)
 
 		if (pr->pr_trace) {
 			if (pr->debug_handler) {
-				pr->debug_handler (prd_trace, pr->debug_data);
+				pr->debug_handler (prd_trace, 0, pr->debug_data);
 			} else {
 				PR_PrintStatement (pr, st, 1);
 			}
@@ -494,7 +493,7 @@ PR_ExecuteProgram (progs_t *pr, func_t fnum)
 
 		if (st->op & OP_BREAK) {
 			if (pr->debug_handler) {
-				pr->debug_handler (prd_breakpoint, pr->debug_data);
+				pr->debug_handler (prd_breakpoint, 0, pr->debug_data);
 			} else {
 				PR_RunError (pr, "breakpoint hit");
 			}
@@ -1714,7 +1713,7 @@ op_call:
 			if (!pr->wp_conditional
 				|| pr->watch->integer_var == pr->wp_val.integer_var) {
 				if (pr->debug_handler) {
-					pr->debug_handler (prd_watchpoint, pr->debug_data);
+					pr->debug_handler (prd_watchpoint, 0, pr->debug_data);
 				} else {
 					PR_RunError (pr, "watchpoint hit: %d -> %d",
 								 old_val.integer_var, pr->watch->integer_var);
diff --git a/libs/gamecode/pr_load.c b/libs/gamecode/pr_load.c
index 9ea30a037..dd405769a 100644
--- a/libs/gamecode/pr_load.c
+++ b/libs/gamecode/pr_load.c
@@ -326,7 +326,6 @@ PR_LoadProgsFile (progs_t *pr, QFile *file, int size)
 			def->type_encoding = xdef->type;
 		}
 	}
-	pr->error_string = 0;
 	pr->pr_trace = 0;
 	pr->pr_trace_depth = 0;
 	pr->pr_xfunction = 0;
@@ -483,15 +482,14 @@ VISIBLE void
 PR_Error (progs_t *pr, const char *error, ...)
 {
 	va_list     argptr;
-	dstring_t  *string = dstring_new ();
+	dstring_t  *string = dstring_new ();//FIXME leaks when debugging
 
 	va_start (argptr, error);
 	dvsprintf (string, error, argptr);
 	va_end (argptr);
 
 	if (pr->debug_handler) {
-		pr->error_string = string->str;
-		pr->debug_handler (prd_error, pr->debug_data);
+		pr->debug_handler (prd_error, string->str, pr->debug_data);
 		// not expected to return, but if so, behave as if there was no handler
 	}
 	Sys_Error ("%s: %s", pr->progs_name, string->str);
diff --git a/ruamoko/qwaq/main.c b/ruamoko/qwaq/main.c
index 46e1d8e4b..8c9650786 100644
--- a/ruamoko/qwaq/main.c
+++ b/ruamoko/qwaq/main.c
@@ -233,7 +233,7 @@ run_progs (void *data)
 	PR_ExecuteProgram (thread->pr, thread->main_func);
 	PR_PopFrame (thread->pr);
 	if (thread->pr->debug_handler) {
-		thread->pr->debug_handler (prd_exit, thread->pr->debug_data);
+		thread->pr->debug_handler (prd_exit, 0, thread->pr->debug_data);
 	}
 	thread->return_code = R_INT (thread->pr);
 	return thread;
diff --git a/ruamoko/qwaq/qwaq-debug.c b/ruamoko/qwaq/qwaq-debug.c
index 40effa817..b7fcab168 100644
--- a/ruamoko/qwaq/qwaq-debug.c
+++ b/ruamoko/qwaq/qwaq-debug.c
@@ -109,7 +109,7 @@ get_target (qwaq_debug_t *debug, const char *name, int handle)
 }
 
 static void
-qwaq_debug_handler (prdebug_t debug_event, void *data)
+qwaq_debug_handler (prdebug_t debug_event, void *param, void *data)
 {
 	__auto_type target = (qwaq_target_t *) data;
 	qwaq_debug_t *debug = target->debugger;
@@ -130,7 +130,7 @@ qwaq_debug_handler (prdebug_t debug_event, void *data)
 	pthread_cond_wait (&target->run_cond.rcond, &target->run_cond.mut);
 	pthread_mutex_unlock (&target->run_cond.mut);
 	if (debug_event == prd_runerror || debug_event == prd_error) {
-		pthread_exit ((void *) target->pr->error_string);
+		pthread_exit (param);
 	}
 }