diff --git a/library/Osmocom_Types.ttcn b/library/Osmocom_Types.ttcn
index 52490ca..8892631 100644
--- a/library/Osmocom_Types.ttcn
+++ b/library/Osmocom_Types.ttcn
@@ -344,5 +344,19 @@
 	}
 }
 
+/* Return a reversed bitstring */
+function f_bits_reversed(in bitstring bits) return bitstring {
+	for (var integer i := 0; i < lengthof(bits) / 2; i := i + 1) {
+		var integer reverse_i := lengthof(bits) - 1 - i;
+		if (i >= reverse_i) {
+			break;
+		}
+		var bitstring tmp;
+		tmp[0] := bits[i];
+		bits[i] := bits[reverse_i];
+		bits[reverse_i] := tmp[0];
+	}
+	return bits;
+}
 
 } with { encode "RAW"; variant "FIELDORDER(msb)" }