diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3c07428f2..9844f1974 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - Fixed `lf viking reader` - search in inverted bitsteam as well (#doegox)
  - Added more default keys (@CONIGUERO)
  - Change `hf 14a info` - it now detects FUDAN (@iceman1001)  Thanks to @secit-pl
  - Fixed support to clone Pyramic, Paradox and Awid on EM4x05 (@doegox)
diff --git a/client/src/cmdlfviking.c b/client/src/cmdlfviking.c
index 6d0a1b913..c58994eef 100644
--- a/client/src/cmdlfviking.c
+++ b/client/src/cmdlfviking.c
@@ -266,28 +266,51 @@ uint64_t getVikingBits(uint32_t id) {
     return ret;
 }
 
+static bool isValidVikingChecksum(uint8_t *src) {
+    uint32_t checkCalc = bytebits_to_byte(src, 8) ^
+                         bytebits_to_byte(src + 8, 8) ^
+                         bytebits_to_byte(src + 16, 8) ^
+                         bytebits_to_byte(src + 24, 8) ^
+                         bytebits_to_byte(src + 32, 8) ^
+                         bytebits_to_byte(src + 40, 8) ^
+                         bytebits_to_byte(src + 48, 8) ^
+                         bytebits_to_byte(src + 56, 8) ^
+                         0xA8;
+    return checkCalc == 0;
+}
+
 // find viking preamble 0xF200 in already demoded data
 int detectViking(uint8_t *src, size_t *size) {
     //make sure buffer has data
     if (*size < 64) return -2;
+    size_t tsize = *size;
     size_t startIdx = 0;
+    bool preamblefound = false;
     uint8_t preamble[] = {1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
-    if (!preambleSearch(src, preamble, sizeof(preamble), size, &startIdx))
-        return -4; //preamble not found
-
-    uint32_t checkCalc = bytebits_to_byte(src + startIdx, 8) ^
-                         bytebits_to_byte(src + startIdx + 8, 8) ^
-                         bytebits_to_byte(src + startIdx + 16, 8) ^
-                         bytebits_to_byte(src + startIdx + 24, 8) ^
-                         bytebits_to_byte(src + startIdx + 32, 8) ^
-                         bytebits_to_byte(src + startIdx + 40, 8) ^
-                         bytebits_to_byte(src + startIdx + 48, 8) ^
-                         bytebits_to_byte(src + startIdx + 56, 8);
-
-    if (checkCalc != 0xA8) return -5;
-    if (*size != 64) return -6;
-    //return start position
-    return (int)startIdx;
+    if (preambleSearch(src, preamble, sizeof(preamble), size, &startIdx)) {
+        preamblefound = true;
+        if (*size != 64) return -6;
+        if (isValidVikingChecksum(src + startIdx)) {
+            //return start position
+            return (int)startIdx;
+        }
+    }
+    // Invert bits and try again
+    *size = tsize;
+    for (uint32_t i = 0; i < *size; i++) src[i] ^= 1;
+    if (preambleSearch(src, preamble, sizeof(preamble), size, &startIdx)) {
+        preamblefound = true;
+        if (*size != 64) return -6;
+        if (isValidVikingChecksum(src + startIdx)) {
+            //return start position
+            return (int)startIdx;
+        }
+    }
+    // Restore buffer
+    *size = tsize;
+    for (uint32_t i = 0; i < *size; i++) src[i] ^= 1;
+    if (preamblefound)
+        return -5;
+    else
+        return -4;
 }
-
-