diff --git a/internal.h b/internal.h
index 9dafcb0f264819..bd77ba864cc270 100644
--- a/internal.h
+++ b/internal.h
@@ -1109,6 +1109,7 @@ VALUE rb_external_str_with_enc(VALUE str, rb_encoding *eenc);
 #define is_ascii_string(str) (rb_enc_str_coderange(str) == ENC_CODERANGE_7BIT)
 #define is_broken_string(str) (rb_enc_str_coderange(str) == ENC_CODERANGE_BROKEN)
 size_t rb_str_memsize(VALUE);
+VALUE rb_sym_proc_call(VALUE args, VALUE sym, int argc, VALUE *argv, VALUE passed_proc);
 
 /* struct.c */
 VALUE rb_struct_init_copy(VALUE copy, VALUE s);
diff --git a/proc.c b/proc.c
index f01d40455ae1c9..98029d024b8a1b 100644
--- a/proc.c
+++ b/proc.c
@@ -1059,6 +1059,7 @@ proc_to_s(VALUE self)
     const char *cname = rb_obj_classname(self);
     const rb_iseq_t *iseq;
     const char *is_lambda;
+    const struct vm_ifunc *ifunc;
 
     GetProcPtr(self, proc);
     iseq = proc->block.iseq;
@@ -1073,6 +1074,10 @@ proc_to_s(VALUE self)
 	str = rb_sprintf("#<%s:%p@%"PRIsVALUE":%d%s>", cname, (void *)self,
 			 iseq->body->location.path, first_lineno, is_lambda);
     }
+    else if ((ifunc = (struct vm_ifunc *)iseq)->func == rb_sym_proc_call) {
+	str = rb_sprintf("#<%s:%p(&%+"PRIsVALUE")%s>", cname, (void *)self,
+			 ID2SYM((ID)ifunc->data), is_lambda);
+    }
     else {
 	str = rb_sprintf("#<%s:%p%s>", cname, (void *)proc->block.iseq,
 			 is_lambda);
diff --git a/string.c b/string.c
index 728676c1597aff..5352a6aab160be 100644
--- a/string.c
+++ b/string.c
@@ -8915,8 +8915,8 @@ sym_to_sym(VALUE sym)
     return sym;
 }
 
-static VALUE
-sym_call(VALUE args, VALUE sym, int argc, VALUE *argv, VALUE passed_proc)
+VALUE
+rb_sym_proc_call(VALUE args, VALUE sym, int argc, VALUE *argv, VALUE passed_proc)
 {
     VALUE obj;
 
@@ -8959,7 +8959,7 @@ sym_to_proc(VALUE sym)
 	return aryp[index + 1];
     }
     else {
-	proc = rb_proc_new(sym_call, (VALUE)id);
+	proc = rb_proc_new(rb_sym_proc_call, (VALUE)id);
 	rb_block_clear_env_self(proc);
 	aryp[index] = sym;
 	aryp[index + 1] = proc;