diff --git a/src/heap_print.rs b/src/heap_print.rs
index cbfbbd495..14ee274d9 100644
--- a/src/heap_print.rs
+++ b/src/heap_print.rs
@@ -1762,7 +1762,7 @@ impl<'a, Outputter: HCValueOutputter> HCPrinter<'a, Outputter> {
         while let Some(loc_data) = self.state_stack.pop() {
             match loc_data {
                 TokenOrRedirect::Atom(atom) => self.print_impromptu_atom(atom),
-                TokenOrRedirect::BarAsOp => append_str!(self, " | "),
+                TokenOrRedirect::BarAsOp => append_str!(self, "|"),
                 TokenOrRedirect::Char(c) => print_char!(self, self.quoted, c),
                 TokenOrRedirect::Op(atom, op) => {
                     self.print_op(&atom.as_str());
diff --git a/tests-pl/iso-conformity-tests.pl b/tests-pl/iso-conformity-tests.pl
index 2f8adec16..bfd74c61b 100644
--- a/tests-pl/iso-conformity-tests.pl
+++ b/tests-pl/iso-conformity-tests.pl
@@ -783,10 +783,10 @@
                         (  op(1105,xfy,'|'),
                            read_from_chars("(a-->b,c|d).", T0),
                            writeq_term_to_chars(T0, C0),
-                           C0 == "a-->b,c | d",
+                           C0 == "a-->b,c|d",
                            read_from_chars("[(a|b)].", T1),
                            writeq_term_to_chars(T1, C1),
-                           C1 == "[(a | b)]",
+                           C1 == "[(a|b)]",
                            read_from_chars("[a,(b,c)|[]].", T2),
                            writeq_term_to_chars(T2, C2),
                            C2 == "[a,(b,c)]"