diff --git a/_codeql_detected_source_root b/_codeql_detected_source_root
new file mode 120000
index 000000000..945c9b46d
--- /dev/null
+++ b/_codeql_detected_source_root
@@ -0,0 +1 @@
+.
\ No newline at end of file
diff --git a/expui/BiorthBasis.cc b/expui/BiorthBasis.cc
index e81f67ffe..e80f1fc57 100644
--- a/expui/BiorthBasis.cc
+++ b/expui/BiorthBasis.cc
@@ -5166,9 +5166,11 @@ namespace BasisClasses
     auto dcpl3 = HighFive::DataSetCreateProps{}; // covariance
 
     // Properties for sample stats
-    if (H5compress) {
+    // Note: Sample stats only use Deflate compression, not Szip
+    if (H5compress > 0) {
       unsigned int csz = sampleCounts.size();
       dcpl1.add(HighFive::Chunking({csz, 1}));
+      // Only apply shuffle filter when Deflate compression is enabled (guaranteed by outer if)
       if (H5shuffle) dcpl1.add(HighFive::Shuffle());
       dcpl1.add(HighFive::Deflate(H5compress));
     }
@@ -5207,7 +5209,7 @@ namespace BasisClasses
     stanza.createAttribute<unsigned>
       ("fullCovar", HighFive::DataSpace::From(icov)).write(icov);
 
-    if (H5compress) {
+    if (H5compress > 0 || H5szip) {
       // Szip parameters
       const int options_mask = H5_SZIP_NN_OPTION_MASK;
       const int pixels_per_block = 8;
@@ -5218,6 +5220,7 @@ namespace BasisClasses
       HighFive::Chunking data_dims2{std::min<unsigned>(csz2, H5chunk), 1};
 
       dcpl2.add(data_dims2);
+      // Only apply shuffle filter when compression is enabled (guaranteed by outer if)
       if (H5shuffle) dcpl2.add(HighFive::Shuffle());
       if (H5szip) {
 	dcpl2.add(HighFive::Szip(options_mask, pixels_per_block));
@@ -5231,6 +5234,7 @@ namespace BasisClasses
       HighFive::Chunking data_dims3{std::min<unsigned>(csz3, H5chunk), 1};
 
       dcpl3.add(data_dims3);
+      // Only apply shuffle filter when compression is enabled (guaranteed by outer if)
       if (H5shuffle) dcpl3.add(HighFive::Shuffle());
       if (H5szip) {
 	dcpl3.add(HighFive::Szip(options_mask, pixels_per_block));
diff --git a/exputil/EmpCylSL.cc b/exputil/EmpCylSL.cc
index 63829ea63..43a856018 100644
--- a/exputil/EmpCylSL.cc
+++ b/exputil/EmpCylSL.cc
@@ -7381,10 +7381,11 @@ void EmpCylSL::WriteH5Cache()
     //
     auto dcpl = HighFive::DataSetCreateProps{};
 
-    if (H5compress) {
+    if (H5compress > 0 || H5szip) {
       // Chunking
       unsigned long nx = NUMX + 1, ny = NUMY + 1;
       dcpl.add(HighFive::Chunking({nx, ny}));
+      // Only apply shuffle filter when compression is enabled (guaranteed by outer if)
       if (H5shuffle) dcpl.add(HighFive::Shuffle());
       if (H5szip) {
         const int options_mask = H5_SZIP_NN_OPTION_MASK;