diff --git a/regression/verilog/expressions/concatenation4.desc b/regression/verilog/expressions/concatenation4.desc
new file mode 100644
index 000000000..a0aec9491
--- /dev/null
+++ b/regression/verilog/expressions/concatenation4.desc
@@ -0,0 +1,9 @@
+KNOWNBUG
+concatenation4.v
+--bound 0
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring
+--
+This should yield an error.
diff --git a/regression/verilog/expressions/concatenation4.v b/regression/verilog/expressions/concatenation4.v
new file mode 100644
index 000000000..1c64f7d86
--- /dev/null
+++ b/regression/verilog/expressions/concatenation4.v
@@ -0,0 +1,7 @@
+module main;
+
+  // 1800-2017 11.4.12
+  // "Unsized constant numbers shall not be allowed in concatenations"
+  wire [31:0] x = { 'b1010 };
+
+endmodule
diff --git a/regression/verilog/expressions/replication2.desc b/regression/verilog/expressions/replication2.desc
new file mode 100644
index 000000000..95e4de9f4
--- /dev/null
+++ b/regression/verilog/expressions/replication2.desc
@@ -0,0 +1,9 @@
+KNOWNBUG
+replication2.v
+--bound 0
+^EXIT=0$
+^SIGNAL=0$
+--
+^warning: ignoring
+--
+This should yield an error.
diff --git a/regression/verilog/expressions/replication2.v b/regression/verilog/expressions/replication2.v
new file mode 100644
index 000000000..fcaa1bdd5
--- /dev/null
+++ b/regression/verilog/expressions/replication2.v
@@ -0,0 +1,8 @@
+module main;
+
+  // The section 11.4.12.1 in 1800-2017 is contained in 11.4.12,
+  // which suggests that the rules there apply to replication operators.
+  // Hence, replications must not use unsized constants.
+  wire [31:0] x = {4{'b1010}};
+
+endmodule