diff --git a/services/clsi/app/js/QuartoRunner.js b/services/clsi/app/js/QuartoRunner.js
index f54048f0cd..1a7b60bebe 100644
--- a/services/clsi/app/js/QuartoRunner.js
+++ b/services/clsi/app/js/QuartoRunner.js
@@ -59,12 +59,13 @@ function _buildQuartoCommand(mainFile) {
   // expected by the rest of the pipeline.
   const inputPath = `$COMPILE_DIR/${mainFile}`
   const baseName = mainFile.replace(/\.[^/.]+$/, '') // strip extension
-  const pdfOut = `$COMPILE_DIR/${baseName}.pdf`
-  const htmlOut = `$COMPILE_DIR/${baseName}.html`
+  // LocalCommandRunner.replace() only replaces the FIRST $COMPILE_DIR
+  // occurrence in the shell string, so the mv commands use relative paths
+  // instead — the shell CWD is already set to the compile directory.
   const cmd =
     `quarto render ${inputPath} --embed-resources 2>&1 && ` +
-    `(mv ${pdfOut} $COMPILE_DIR/output.pdf 2>/dev/null || ` +
-    `mv ${htmlOut} $COMPILE_DIR/output.html 2>/dev/null)`
+    `(mv ${baseName}.pdf output.pdf 2>/dev/null || ` +
+    `mv ${baseName}.html output.html 2>/dev/null)`
   return ['/bin/sh', '-c', cmd]
 }