diff --git a/armsrc/lfops.c b/armsrc/lfops.c
index 0716efc60..e81d5570c 100644
--- a/armsrc/lfops.c
+++ b/armsrc/lfops.c
@@ -1316,10 +1316,6 @@ int lf_hid_watch(int findone, uint32_t *high, uint32_t *low, bool ledcontrol) {
                         cardnum = (lo >> 1) & 0xFFFF;
                         fac = (lo >> 17) & 0xFF;
                     }
-                    if (bitlen == 37) {
-                        cardnum = (lo >> 1) & 0x7FFFF;
-                        fac = ((hi & 0xF) << 12) | (lo >> 20);
-                    }
                     if (bitlen == 34) {
                         cardnum = (lo >> 1) & 0xFFFF;
                         fac = ((hi & 1) << 15) | (lo >> 17);
diff --git a/client/src/cmdhficlass.c b/client/src/cmdhficlass.c
index 22b90834e..492403344 100644
--- a/client/src/cmdhficlass.c
+++ b/client/src/cmdhficlass.c
@@ -1451,8 +1451,7 @@ static int iclass_decode_credentials_new_pacs(uint8_t *d) {
 
     PrintAndLogEx(NORMAL, "");
     PrintAndLogEx(INFO, "Wiegand decode");
-    wiegand_message_t packed = initialize_message_object(top, mid, bot, 0);
-    HIDTryUnpack(&packed);
+    decode_wiegand(top, mid, bot, 0);
 
     return PM3_SUCCESS;
 }
@@ -1492,8 +1491,7 @@ static void iclass_decode_credentials(uint8_t *data) {
             PrintAndLogEx(SUCCESS, "Binary..................... " _GREEN_("%s"), pbin);
 
             PrintAndLogEx(INFO, "Wiegand decode");
-            wiegand_message_t packed = initialize_message_object(top, mid, bot, 0);
-            HIDTryUnpack(&packed);
+            decode_wiegand(top, mid, bot, 0);
         }
 
     } else {
@@ -2916,8 +2914,7 @@ static int CmdHFiClass_ReadBlock(const char *Cmd) {
                     PrintAndLogEx(SUCCESS, "      bin : %s", pbin);
                     PrintAndLogEx(INFO, "");
                     PrintAndLogEx(INFO, "------------------------------ " _CYAN_("Wiegand") " -------------------------------");
-                    wiegand_message_t packed = initialize_message_object(top, mid, bot, 0);
-                    HIDTryUnpack(&packed);
+                    decode_wiegand(top, mid, bot, 0);
                 }
             } else {
                 PrintAndLogEx(INFO, "no credential found");
diff --git a/client/src/cmdhfmf.c b/client/src/cmdhfmf.c
index b80fb138e..b17e9caf8 100644
--- a/client/src/cmdhfmf.c
+++ b/client/src/cmdhfmf.c
@@ -6293,8 +6293,7 @@ static int CmdHF14AMfMAD(const char *Cmd) {
                 PrintAndLogEx(SUCCESS, "Binary... " _GREEN_("%s"), pbin);
 
                 PrintAndLogEx(INFO, "Wiegand decode");
-                wiegand_message_t packed = initialize_message_object(top, mid, bot, 0);
-                HIDTryUnpack(&packed);
+                decode_wiegand(top, mid, bot, 0);
             }
         }
 
diff --git a/client/src/cmdlfhid.c b/client/src/cmdlfhid.c
index baed95b29..fb1eeb56e 100644
--- a/client/src/cmdlfhid.c
+++ b/client/src/cmdlfhid.c
@@ -160,8 +160,7 @@ int demodHID(bool verbose) {
         return PM3_ESOFT;
     }
 
-    wiegand_message_t packed = initialize_message_object(hi2, hi, lo, 0);
-    if (HIDTryUnpack(&packed) == false) {
+    if (!decode_wiegand(hi2, hi, lo, 0)) { // if failed to unpack wiegand
         printDemodBuff(0, false, false, true);
     }
     PrintAndLogEx(INFO, "raw: " _GREEN_("%08x%08x%08x"), hi2, hi, lo);
@@ -214,8 +213,8 @@ static int CmdHIDReader(const char *Cmd) {
     }
 
     do {
-        lf_read(false, 16000);
-        demodHID(!cm);
+        lf_read(false, 16000); // get data of 16000 samples from proxmark device
+        demodHID(!cm); // demod data and print results if found
     } while (cm && !kbd_enter_pressed());
 
     return PM3_SUCCESS;
diff --git a/client/src/cmdwiegand.c b/client/src/cmdwiegand.c
index 9fc06b6f9..7853b71cd 100644
--- a/client/src/cmdwiegand.c
+++ b/client/src/cmdwiegand.c
@@ -160,8 +160,7 @@ int CmdWiegandDecode(const char *Cmd) {
         return PM3_EINVARG;
     }
 
-    wiegand_message_t packed = initialize_message_object(top, mid, bot, blen);
-    HIDTryUnpack(&packed);
+    decode_wiegand(top, mid, bot, blen);
     return PM3_SUCCESS;
 }
 
diff --git a/client/src/wiegand_formats.c b/client/src/wiegand_formats.c
index 0b600f804..b64aa0e74 100644
--- a/client/src/wiegand_formats.c
+++ b/client/src/wiegand_formats.c
@@ -1534,18 +1534,18 @@ bool HIDTryUnpack(wiegand_message_t *packed) {
 
             found_cnt++;
             hid_print_card(&card, FormatTable[i]);
-
-            if (FormatTable[i].Fields.hasParity || card.ParityValid == false)
+            // if fields has parity AND card parity is false
+            if (FormatTable[i].Fields.hasParity && (card.ParityValid == false))
                 found_invalid_par++;
         }
         ++i;
     }
 
     if (found_cnt) {
-        PrintAndLogEx(INFO, "found %u matching format%c", found_cnt, (found_cnt > 1) ? 's' : ' ');
+        PrintAndLogEx(INFO, "found %u matching format%c with bit len %d", found_cnt, (found_cnt > 1) ? 's' : ' ', packed->Length);
     }
-
-    if (packed->Length && found_invalid_par == 0) {
+    
+    if (packed->Length && ((found_cnt - found_invalid_par) == 0)) { // if length > 0 and no valid parity matches
         PrintAndLogEx(WARNING, "Wiegand unknown bit len %d", packed->Length);
         PrintAndLogEx(HINT, "Try 0xFFFF's http://cardinfo.barkweb.com.au/");
     }
@@ -1561,6 +1561,31 @@ void HIDUnpack(int idx, wiegand_message_t *packed) {
     }
 }
 
+// decode wiegand format using HIDTryUnpack
+// return true if at least one valid matching formats found
+bool decode_wiegand(uint32_t top, uint32_t mid, uint32_t bot, int n) {
+    bool decode_result;
+    
+    if (top == 0 && mid == 0 && bot == 0) {
+        decode_result = false;
+    } else if ((n > 0) || ((mid & 0xFFFFFFC0) > 0)) {  // if n > 0 or there's more than 38 bits
+        wiegand_message_t packed = initialize_message_object(top, mid, bot, n);
+        decode_result = HIDTryUnpack(&packed);
+    } else { // n <= 0 and 39-64 bits are all 0, try two possible bitlens
+        wiegand_message_t packed1 = initialize_message_object(top, mid, bot, n); // 26-37 bits
+        wiegand_message_t packed2 = initialize_message_object(top, mid, bot, 38); // 38 bits
+        bool packed1_result = HIDTryUnpack(&packed1);
+        bool packed2_result = HIDTryUnpack(&packed2);
+        decode_result = (packed1_result || packed2_result);
+    }
+
+    if (decode_result == false) {
+        PrintAndLogEx(DEBUG, "DEBUG: Error - " _RED_("HID no values found"));
+    }
+
+    return decode_result;
+}
+
 int HIDDumpPACSBits(const uint8_t *const data, const uint8_t length, bool verbose) {
     uint8_t n = length - 1;
     uint8_t pad = data[0];
diff --git a/client/src/wiegand_formats.h b/client/src/wiegand_formats.h
index ff231f25f..503e85daf 100644
--- a/client/src/wiegand_formats.h
+++ b/client/src/wiegand_formats.h
@@ -58,6 +58,7 @@ bool HIDPack(int format_idx, wiegand_card_t *card, wiegand_message_t *packed, bo
 bool HIDTryUnpack(wiegand_message_t *packed);
 void HIDPackTryAll(wiegand_card_t *card, bool preamble);
 void HIDUnpack(int idx, wiegand_message_t *packed);
+bool decode_wiegand(uint32_t top, uint32_t mid, uint32_t bot, int n);
 int HIDDumpPACSBits(const uint8_t *const data, const uint8_t length, bool verbose);
 void print_wiegand_code(wiegand_message_t *packed);
 void print_desc_wiegand(cardformat_t *fmt, wiegand_message_t *packed);
diff --git a/client/src/wiegand_formatutils.c b/client/src/wiegand_formatutils.c
index f77ab5bfe..fed31d9fb 100644
--- a/client/src/wiegand_formatutils.c
+++ b/client/src/wiegand_formatutils.c
@@ -132,7 +132,23 @@ static uint8_t get_length_from_header(wiegand_message_t *data) {
     /**
      * detect if message has "preamble" / "sentinel bit"
      * Right now we just calculate the highest bit set
-     * 37 bit formats is hard to detect since it doesnt have a sentinel bit
+     * 38 bits format is handled by directly setting n=38 in initialize_message_object()
+     * since it's hard to distinguish 38 bits with formats with preamble bit (26-36 bits)
+     * 
+     * (from http://www.proxmark.org/forum/viewtopic.php?pid=5368#p5368)
+     * 0000 0010 0000 0000 01xx xxxx xxxx xxxx xxxx xxxx xxxx  26-bit
+     * 0000 0010 0000 0000 1xxx xxxx xxxx xxxx xxxx xxxx xxxx  27-bit
+     * 0000 0010 0000 0001 xxxx xxxx xxxx xxxx xxxx xxxx xxxx  28-bit
+     * 0000 0010 0000 001x xxxx xxxx xxxx xxxx xxxx xxxx xxxx  29-bit
+     * 0000 0010 0000 01xx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  30-bit
+     * 0000 0010 0000 1xxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  31-bit
+     * 0000 0010 0001 xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  32-bit
+     * 0000 0010 001x xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  33-bit
+     * 0000 0010 01xx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  34-bit
+     * 0000 0010 1xxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  35-bit
+     * 0000 0011 xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  36-bit
+     * 0000 000x xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  37-bit
+     * 0000 00xx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx  38-bit
      */
     uint8_t len = 0;
     uint32_t hfmt = 0; // for calculating card length
@@ -140,26 +156,23 @@ static uint8_t get_length_from_header(wiegand_message_t *data) {
     if ((data->Top & 0x000FFFFF) > 0) { // > 64 bits
         hfmt = data->Top & 0x000FFFFF;
         len = 64;
-    } else if (data->Mid > 0) { // < 63-32 bits
-
+    } else if (data->Mid > 0) { 
         // detect HID format b38 set
-        if (data->Mid & 0xFFFFFFC0) {
+        if (data->Mid & 0xFFFFFFC0) { // 39-64 bits
             hfmt = data->Mid;
-            len = 32;
-        } else {
-
+            len = 31; // remove leading 1 (preamble) in 39-64 bits format
+        } else { // detect card format 26-37 bits using "preamble" / "sentinel bit"
             PrintAndLogEx(DEBUG, "hid preamble detected");
-            len = 32;
-
-            if ((data->Mid ^ 0x20) == 0) { hfmt = data->Bot; len = 0; }
-            else if ((data->Mid & 0x10) == 0) { hfmt = data->Mid & 0x1F; }
-            else if ((data->Mid & 0x08) == 0) { hfmt = data->Mid & 0x0F; }
-            else if ((data->Mid & 0x04) == 0) { hfmt = data->Mid & 0x07; }
-            else if ((data->Mid & 0x02) == 0) { hfmt = data->Mid & 0x03; }
-            else if ((data->Mid & 0x01) == 0) { hfmt = data->Mid & 0x01; }
-            else { hfmt = data->Mid & 0x3F;}
-        }
 
+            // if bit 38 is set: => 26-36 bits
+            if (((data->Mid >> 5) & 1) == 1) { 
+                hfmt = (((data->Mid & 31) << 12) | (data->Bot >> 26)); //get bits 27-37 to check for format len bit
+                len = 19;
+            } else { // if bit 38 is not set => 37 bits
+                hfmt = 0;
+                len = 37;
+            }  
+        } 
     } else {
         hfmt = data->Bot;
         len = 0;