diff --git a/passes/techmap/techmap.cc b/passes/techmap/techmap.cc
index cf40b2f17..1d0362ad6 100644
--- a/passes/techmap/techmap.cc
+++ b/passes/techmap/techmap.cc
@@ -224,7 +224,7 @@ struct TechmapWorker
 
 					for (auto bit : sigmaps.at(tpl)(it.second))
 						if (bit.wire != nullptr)
-							autopurge_tpl_bits.insert(it.second);
+							autopurge_tpl_bits.insert(bit);
 				}
 			}
 			IdString w_name = it.second->name;
@@ -359,6 +359,12 @@ struct TechmapWorker
 				for (auto &attr : w->attributes) {
 					if (attr.first == ID(src))
 						continue;
+					auto lhs = GetSize(extra_connect.first);
+					auto rhs = GetSize(extra_connect.second);
+					if (lhs > rhs)
+						extra_connect.first.remove(rhs, lhs-rhs);
+					else if (rhs > lhs)
+						extra_connect.second.remove(lhs, rhs-lhs);
 					module->connect(extra_connect);
 					break;
 				}
diff --git a/tests/techmap/autopurge.ys b/tests/techmap/autopurge.ys
new file mode 100644
index 000000000..1eb99ec37
--- /dev/null
+++ b/tests/techmap/autopurge.ys
@@ -0,0 +1,62 @@
+# https://github.com/YosysHQ/yosys/issues/1381
+read_verilog <<EOT
+module sub(input i, output o, (* techmap_autopurge *) input j);
+foobar f(i, o, j);
+endmodule
+EOT
+design -stash techmap
+
+read_verilog <<EOT
+(* blackbox *)
+module sub(input i, output o, input j);
+endmodule
+
+(* blackbox *)
+module foobar(input i, output o, input j);
+endmodule
+
+module top(input i, output o);
+sub s0(i, o);
+endmodule
+EOT
+
+techmap -map %techmap
+hierarchy
+check -assert
+
+# https://github.com/YosysHQ/yosys/issues/1391
+design -reset
+read_verilog <<EOT
+module sub(input i, output o, (* techmap_autopurge *) input [1:0] j);
+foobar f(i, o, j);
+endmodule
+EOT
+design -stash techmap
+
+read_verilog <<EOT
+(* blackbox *)
+module sub(input i, output o, input j);
+endmodule
+
+(* blackbox *)
+module foobar(input i, output o, input j);
+endmodule
+
+module top(input i, output o);
+sub s0(i, o);
+endmodule
+EOT
+
+techmap -map %techmap
+hierarchy
+check -assert
+
+read_verilog -overwrite <<EOT
+module top(input i, output o);
+wire j;
+sub s0(i, o, j);
+endmodule
+EOT
+
+techmap -map %techmap
+hierarchy