diff --git a/common/commonutil.c b/common/commonutil.c
index be7576a8c..f9f039df1 100644
--- a/common/commonutil.c
+++ b/common/commonutil.c
@@ -144,6 +144,13 @@ uint32_t reflect32(uint32_t b) {
     return v;
 }
 
+uint64_t reflect48(uint64_t v) {
+    uint64_t vhi = reflect16(v >> 32);
+    uint64_t vlo = reflect32(v);
+    v = (vlo << 32) | (vhi & 0xFFFF);
+    return v;
+}
+
 uint64_t reflect64(uint64_t b) {
     // https://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
     uint64_t v = b; // 64-bit word to reverse bit order
diff --git a/common/commonutil.h b/common/commonutil.h
index 62b1b78e7..a3476a284 100644
--- a/common/commonutil.h
+++ b/common/commonutil.h
@@ -74,6 +74,7 @@ uint32_t reflect(uint32_t v, int b); // used in crc.c ...
 uint8_t reflect8(uint8_t b);         // dedicated 8bit reversal
 uint16_t reflect16(uint16_t b);      // dedicated 16bit reversal
 uint32_t reflect32(uint32_t b);      // dedicated 32bit reversal
+uint64_t reflect48(uint64_t b);      // dedicated 48bit reversal
 uint64_t reflect64(uint64_t b);      // dedicated 64bit reversal
 
 void num_to_bytes(uint64_t n, size_t len, uint8_t *dest);