diff --git a/tools/clang/unittests/HLSLExec/LongVectorOps.def b/tools/clang/unittests/HLSLExec/LongVectorOps.def
index 002b84a1f2..d0a53c7a7d 100644
--- a/tools/clang/unittests/HLSLExec/LongVectorOps.def
+++ b/tools/clang/unittests/HLSLExec/LongVectorOps.def
@@ -129,6 +129,7 @@ OP_DEFAULT_DEFINES(UnaryMath, Frexp, 1, "TestFrexp", "", " -DFUNC_FREXP=1")
 OP_DEFAULT(FloatSpecial, IsFinite, 1, "isfinite", "")
 OP_DEFAULT(FloatSpecial, IsInf, 1, "isinf", "")
 OP_DEFAULT(FloatSpecial, IsNan, 1, "isnan", "")
+OP_DEFAULT_DEFINES(FloatSpecial, ModF, 1, "TestModF", "", " -DFUNC_TEST_MODF=1")
 
 OP_DEFAULT(BinaryComparison, LessThan, 2, "", "<")
 OP_DEFAULT(BinaryComparison, LessEqual, 2, "", "<=")
diff --git a/tools/clang/unittests/HLSLExec/LongVectors.cpp b/tools/clang/unittests/HLSLExec/LongVectors.cpp
index dce99fd647..956cde347f 100644
--- a/tools/clang/unittests/HLSLExec/LongVectors.cpp
+++ b/tools/clang/unittests/HLSLExec/LongVectors.cpp
@@ -1236,6 +1236,41 @@ FLOAT_SPECIAL_OP(OpType::IsInf, (std::isinf(A)));
 FLOAT_SPECIAL_OP(OpType::IsNan, (std::isnan(A)));
 #undef FLOAT_SPECIAL_OP
 
+template <typename T> struct Op<OpType::ModF, T, 1> : DefaultValidation<T> {};
+
+template <typename T> static T modF(T Input, T &OutParam);
+
+template <> float modF(float Input, float &OutParam) {
+  return std::modf(Input, &OutParam);
+}
+
+template <> HLSLHalf_t modF(HLSLHalf_t Input, HLSLHalf_t &OutParam) {
+  float Exp = 0.0f;
+  float Man = std::modf(float(Input), &Exp);
+  OutParam = HLSLHalf_t(Exp);
+  return Man;
+}
+
+template <typename T> struct ExpectedBuilder<OpType::ModF, T> {
+  static std::vector<T> buildExpected(Op<OpType::ModF, T, 1> &,
+                                      const InputSets<T> &Inputs) {
+    DXASSERT_NOMSG(Inputs.size() == 1);
+    size_t VectorSize = Inputs[0].size();
+
+    std::vector<T> Expected;
+    Expected.resize(VectorSize * 2);
+
+    for (size_t I = 0; I < VectorSize; ++I) {
+      T Exp;
+      T Man = modF(Inputs[0][I], Exp);
+      Expected[I] = Man;
+      Expected[I + VectorSize] = Exp;
+    }
+
+    return Expected;
+  }
+};
+
 //
 // dispatchTest
 //
@@ -1772,10 +1807,12 @@ class DxilConf_SM69_Vectorized {
   HLK_TEST(IsFinite, HLSLHalf_t);
   HLK_TEST(IsInf, HLSLHalf_t);
   HLK_TEST(IsNan, HLSLHalf_t);
+  HLK_TEST(ModF, HLSLHalf_t);
 
   HLK_TEST(IsFinite, float);
   HLK_TEST(IsInf, float);
   HLK_TEST(IsNan, float);
+  HLK_TEST(ModF, float);
 
   // Binary Comparison
 
diff --git a/tools/clang/unittests/HLSLExec/ShaderOpArith.xml b/tools/clang/unittests/HLSLExec/ShaderOpArith.xml
index f89a87ca68..43fe5d6412 100644
--- a/tools/clang/unittests/HLSLExec/ShaderOpArith.xml
+++ b/tools/clang/unittests/HLSLExec/ShaderOpArith.xml
@@ -4112,6 +4112,20 @@ void MSMain(uint GID : SV_GroupIndex,
         }
         #endif
 
+        #ifdef FUNC_TEST_MODF
+        vector<OUT_TYPE, NUM> TestModF(vector<TYPE, NUM> Vector)
+        {
+          vector<OUT_TYPE, NUM> Mantissa;
+          vector<OUT_TYPE, NUM> Exponent;
+
+          Mantissa = modf(Vector, Exponent);
+
+          g_OutputVector.Store< vector<OUT_TYPE, NUM> >(sizeof(OUT_TYPE) * NUM, Exponent);
+
+          return Mantissa;
+        }
+        #endif
+
         #ifdef FUNC_SHUFFLE_VECTOR
         vector<OUT_TYPE, NUM> TestShuffleVector(TYPE Scalar)
         {