diff --git a/NXDNConvolution.cpp b/NXDNConvolution.cpp
index 8db6a05..d5292fc 100755
--- a/NXDNConvolution.cpp
+++ b/NXDNConvolution.cpp
@@ -21,6 +21,7 @@
 #include <cstdio>
 #include <cassert>
 #include <cstring>
+#include <cmath>
 
 const unsigned char BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
 
@@ -72,7 +73,7 @@ void CNXDNConvolution::decode(uint8_t s0, uint8_t s1)
   for (uint8_t i = 0U; i < NUM_OF_STATES_D2; i++) {
     uint8_t j = i * 2U;
 
-    uint16_t metric = abs(BRANCH_TABLE1[i] - s0) + abs(BRANCH_TABLE2[i] - s1);
+    uint16_t metric = ::abs(BRANCH_TABLE1[i] - s0) + ::abs(BRANCH_TABLE2[i] - s1);
 
     uint16_t m0 = m_oldMetrics[i] + metric;
     uint16_t m1 = m_oldMetrics[i + NUM_OF_STATES_D2] + (M - metric);