diff --git a/src/bej_common.c b/src/bej_common.c
index 1d3be07..0e1cf10 100644
--- a/src/bej_common.c
+++ b/src/bej_common.c
@@ -23,3 +23,22 @@
     // In nnint, first byte indicate how many bytes are there.
     return *nnint + sizeof(uint8_t);
 }
+
+uint8_t bejNnintEncodingSizeOfUInt(uint64_t val)
+{
+    uint8_t bytes = 0;
+    do
+    {
+        // Even if the value is 0, we need a byte for that.
+        ++bytes;
+        val = val >> 8;
+    } while (val != 0);
+    // Need 1 byte to add the nnint length.
+    return bytes + 1;
+}
+
+uint8_t bejNnintLengthFieldOfUInt(uint64_t val)
+{
+    // From the size of the encoded value, we need 1 byte for the length field.
+    return bejNnintEncodingSizeOfUInt(val) - 1;
+}