1 files changed, 4 insertions, 2 deletions
diff --git a/thread.c b/thread.c
index c3bfbd76fa..cb05c2c40f 100644
--- a/thread.c
+++ b/thread.c
@@ -5254,11 +5254,13 @@ update_line_coverage(VALUE data, const rb_trace_arg_t *trace_arg)
 static void
 update_branch_coverage(VALUE data, const rb_trace_arg_t *trace_arg)
 {
-    VALUE coverage = rb_iseq_coverage(GET_EC()->cfp->iseq);
+    const rb_control_frame_t *cfp = GET_EC()->cfp;
+    VALUE coverage = rb_iseq_coverage(cfp->iseq);
     if (RB_TYPE_P(coverage, T_ARRAY) && !RBASIC_CLASS(coverage)) {
 	VALUE branches = RARRAY_AREF(coverage, COVERAGE_INDEX_BRANCHES);
 	if (branches) {
-	    long idx = FIX2INT(trace_arg->data), count;
+            long pc = cfp->pc - cfp->iseq->body->iseq_encoded - 1;
+            long idx = FIX2INT(RARRAY_AREF(ISEQ_PC2BRANCHINDEX(cfp->iseq), pc)), count;
 	    VALUE counters = RARRAY_AREF(branches, 1);
 	    VALUE num = RARRAY_AREF(counters, idx);
 	    count = FIX2LONG(num) + 1;