diff --git a/tools/clang/unittests/HLSLExec/LinAlgTests.cpp b/tools/clang/unittests/HLSLExec/LinAlgTests.cpp
index 961cc4f8a1..7b8aeeeba7 100644
--- a/tools/clang/unittests/HLSLExec/LinAlgTests.cpp
+++ b/tools/clang/unittests/HLSLExec/LinAlgTests.cpp
@@ -28,6 +28,10 @@
 #include <optional>
 #include <sstream>
 #include <string>
+
+#define STREAM_FLOAT(stream, name, value)                                      \
+  stream << std::showpoint << " -D" << name << "=" << value << "F"             \
+         << std::noshowpoint
 #include <variant>
 #include <vector>
 
@@ -505,7 +509,7 @@ static void runSplatStore(ID3D12Device *Device,
   const size_t BufferSize = Params.totalBytes();
 
   std::stringstream ExtraDefs;
-  ExtraDefs << "-DFILL_VALUE=" << FillValue;
+  STREAM_FLOAT(ExtraDefs, "FILL_VALUE", FillValue);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());
 
@@ -624,7 +628,7 @@ static const char ElementAccessShader[] = R"(
   // flatten the 2D index into a 1D index then scale by element size
   // Always store row-major and work it out in the test runner
   uint coordToByteOffset(uint2 coord) {
-    return (coord.y * M_DIM + coord.x) * ELEM_SIZE;
+    return (coord.x * N_DIM + coord.y) * ELEM_SIZE;
   }
 
   [WaveSize(4, 64)]
@@ -936,8 +940,8 @@ static void runMatMatMul(ID3D12Device *Device,
 
   std::stringstream ExtraDefs;
   ExtraDefs << " -DK_DIM=" << K;
-  ExtraDefs << " -DA_FILL=" << AFill;
-  ExtraDefs << " -DB_FILL=" << BFill;
+  STREAM_FLOAT(ExtraDefs, "A_FILL", AFill);
+  STREAM_FLOAT(ExtraDefs, "B_FILL", BFill);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());
 
@@ -1018,9 +1022,9 @@ static void runMatMatMulAccum(ID3D12Device *Device,
 
   std::stringstream ExtraDefs;
   ExtraDefs << " -DK_DIM=" << K;
-  ExtraDefs << " -DA_FILL=" << AFill;
-  ExtraDefs << " -DB_FILL=" << BFill;
-  ExtraDefs << " -DC_FILL=" << CFill;
+  STREAM_FLOAT(ExtraDefs, "A_FILL", AFill);
+  STREAM_FLOAT(ExtraDefs, "B_FILL", BFill);
+  STREAM_FLOAT(ExtraDefs, "C_FILL", CFill);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());
 
@@ -1094,8 +1098,8 @@ static void runMatAccum(ID3D12Device *Device,
   const size_t BufferSize = Params.totalBytes();
 
   std::stringstream ExtraDefs;
-  ExtraDefs << " -DLHS_FILL=" << LHSFill;
-  ExtraDefs << " -DRHS_FILL=" << RHSFill;
+  STREAM_FLOAT(ExtraDefs, "LHS_FILL", LHSFill);
+  STREAM_FLOAT(ExtraDefs, "RHS_FILL", RHSFill);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());
 
@@ -1552,7 +1556,7 @@ static void runStoreMemory(ID3D12Device *Device,
 
   std::stringstream ExtraDefs;
   ExtraDefs << " -DOFFSET=" << 0;
-  ExtraDefs << " -DFILL_VALUE=" << FillValue;
+  STREAM_FLOAT(ExtraDefs, "FILL_VALUE", FillValue);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());
 
@@ -1632,7 +1636,7 @@ static void runAccumulateMemory(ID3D12Device *Device,
 
   std::stringstream ExtraDefs;
   ExtraDefs << " -DOFFSET=" << 0;
-  ExtraDefs << " -DFILL_VALUE=" << FillValue;
+  STREAM_FLOAT(ExtraDefs, "FILL_VALUE", FillValue);
 
   std::string Args = buildCompilerArgs(Params, ExtraDefs.str().c_str());