diff --git a/src/UpperPHY/LDPC/ldpc_rate_recovery.cpp b/src/UpperPHY/LDPC/ldpc_rate_recovery.cpp
index 400bd640cb26689a21d77a00ed2d6da0d1c8459f..c46165e5cea2487d46a3b0e3f0837fb1c4c37c59 100644
--- a/src/UpperPHY/LDPC/ldpc_rate_recovery.cpp
+++ b/src/UpperPHY/LDPC/ldpc_rate_recovery.cpp
@@ -43,6 +43,12 @@ void undo_selection(uint32_t z, uint32_t n, uint32_t e,
       out[k0] = in[k_idx++];
     }
   }
+
+  // set filler bits
+  if (len_filler_bits > 0) {
+    memset(&out[len_s_bits], INT8_MAX, len_filler_bits * sizeof(int8_t));
+  }
+
   // offset k0 to skip filler bits
   if (k0 >= len_s_bits && k0 < len_s_bits + len_filler_bits) {
     k0 = len_s_bits + len_filler_bits;
diff --git a/test/LDPC/rate_recovery/main.cpp b/test/LDPC/rate_recovery/main.cpp
index 3a399b132b8cb8af16f0b7addf48fc01806247de..1993a3d9567bf5916ffc235f91fb0cbd1a70a080 100644
--- a/test/LDPC/rate_recovery/main.cpp
+++ b/test/LDPC/rate_recovery/main.cpp
@@ -39,6 +39,12 @@ void ref_undo_selection(uint32_t z, uint32_t n, uint32_t e,
       out[k0] = in[k_idx++];
     }
   }
+
+  // set filler bits
+  if (len_filler_bits > 0) {
+    memset(&out[len_s_bits], INT8_MAX, len_filler_bits * sizeof(int8_t));
+  }
+
   // offset k0 to skip filler bits
   if (k0 >= len_s_bits && k0 < len_s_bits + len_filler_bits) {
     k0 = len_s_bits + len_filler_bits;
@@ -267,7 +273,7 @@ bool test_ref_rate_recovery() {
       passed &= (in_filler[j] == out_filler[i]);
       j++;
     } else if ((i >= (z * 10 - 2 * z - f)) && (i < (z * 10 - 2 * z))) {
-      passed &= (0 == out_filler[i]);
+      passed &= (INT8_MAX == out_filler[i]);
     } else if (n <= e) {
       passed &= (in_filler[j] == out_filler[i]);
       j++;