diff --git a/include/hip/hcc_detail/math_functions.h b/include/hip/hcc_detail/math_functions.h
index 5482f34093..e717df07c1 100644
--- a/include/hip/hcc_detail/math_functions.h
+++ b/include/hip/hcc_detail/math_functions.h
@@ -57,6 +57,7 @@ __device__ float exp2f(float x);
 __device__ float expf(float x);
 __device__ float expm1f(float x);
 __device__ int abs(int x);
+__device__ long long abs(long long x);
 __device__ float fabsf(float x);
 __device__ float fdimf(float x, float y);
 __device__ float fdividef(float x, float y);
diff --git a/src/hip_fp16.cpp b/src/hip_fp16.cpp
index e4c1b43786..3004b7805d 100644
--- a/src/hip_fp16.cpp
+++ b/src/hip_fp16.cpp
@@ -29,10 +29,6 @@ struct hipHalfHolder {
     };
 };
 
-#define HINF 65504
-
-__device__ static struct hipHalfHolder __hInfValue = {HINF};
-
 __device__ __half __hadd(__half a, __half b) { return a + b; }
 
 __device__ __half __hadd_sat(__half a, __half b) { return a + b; }
@@ -63,9 +59,21 @@ __device__ bool __hge(__half a, __half b) { return a >= b ? true : false; }
 
 __device__ bool __hgt(__half a, __half b) { return a > b ? true : false; }
 
-__device__ bool __hisinf(__half a) { return a == HINF ? true : false; }
+__device__ bool __hisinf(__half a) {
+  hipHalfHolder hH;
+  hH.h = a;
+  // mask with 0x7fff to drop the sign bit
+  // 0x7c00 is bit pattern for inf (exp = 11111, significand = 0)
+  return ((hH.s & 0x7fff) == 0x7c00) ? true : false;
+}
 
-__device__ bool __hisnan(__half a) { return a > HINF ? true : false; }
+__device__ bool __hisnan(__half a) {
+  hipHalfHolder hH;
+  hH.h = a;
+  // mask with 0x7fff to drop the sign bit
+  // 0x7cXX is bit pattern for inf (exp = 11111, significand = 0)
+  return ((hH.s & 0x7fff) > 0x7c00) ? true : false;
+}
 
 __device__ bool __hle(__half a, __half b) { return a <= b ? true : false; }
 
@@ -124,8 +132,8 @@ __device__ __half2 __hgt2(__half2 a, __half2 b) {
 
 __device__ __half2 __hisnan2(__half2 a) {
     __half2 c;
-    c.x = (a.x > HINF) ? (__half)1 : (__half)0;
-    c.y = (a.y > HINF) ? (__half)1 : (__half)0;
+    c.x = (__hisnan(a.x)) ? (__half)1 : (__half)0;
+    c.y = (__hisnan(a.y)) ? (__half)1 : (__half)0;
     return c;
 }
 
diff --git a/src/math_functions.cpp b/src/math_functions.cpp
index 3c0a7f6541..dedc40f2ae 100644
--- a/src/math_functions.cpp
+++ b/src/math_functions.cpp
@@ -56,6 +56,9 @@ __device__ float expm1f(float x) { return hc::precise_math::expm1f(x); }
 __device__ int abs(int x) {
     return x >= 0 ? x : -x;  // TODO - optimize with OCML
 }
+__device__ long long abs(long long x) {
+    return x >= 0 ? x : -x;  
+}
 __device__ float fabsf(float x) { return hc::precise_math::fabsf(x); }
 __device__ float fdimf(float x, float y) { return hc::precise_math::fdimf(x, y); }
 __device__ float fdividef(float x, float y) { return x / y; }
@@ -220,14 +223,7 @@ __device__ double j0(double x) { return __hip_j0(x); }
 __device__ double j1(double x) { return __hip_j1(x); }
 __device__ double jn(int n, double x) { return __hip_jn(n, x); }
 __device__ double ldexp(double x, int exp) { return hc::precise_math::ldexp(x, exp); }
-__device__ double lgamma(double x) {
-    double val = 0.0;
-    double y = x - 1;
-    while (y > 0) {
-        val += log(y--);
-    }
-    return val;
-}
+__device__ double lgamma(double x) { return hc::precise_math::lgamma(x); }
 __device__ long long int llrint(double x) {
     long long int y = hc::precise_math::round(x);
     return y;