diff --git a/news/changelog-1.11.md b/news/changelog-1.11.md
index 4c11a6001e4..4bdbaf50d21 100644
--- a/news/changelog-1.11.md
+++ b/news/changelog-1.11.md
@@ -1,3 +1,5 @@
 All changes included in 1.11:
 
+## Regression fixes
 
+- ([#14731](https://github.com/quarto-dev/quarto-cli/pull/14731)): Fix `QUARTO_VENDOR_BINARIES=false` builds silently succeeding with missing binaries. The `configure` step's "is it on PATH?" check for `typst-gather`, `typst`, `pandoc` and `esbuild` compared an unawaited `Promise` against `undefined`, so the guard never fired. A build with `typst-gather` neither vendored nor on PATH reported success and produced a Quarto tree without it, surfacing only at render time as `typst-gather analyze failed; staging all packages as fallback`. The missing-binary error message now also names the path that was checked and the `QUARTO_TYPST_GATHER` environment variable.
diff --git a/package/src/common/dependencies/esbuild.ts b/package/src/common/dependencies/esbuild.ts
index 335e90050b0..cbdfd9266c6 100644
--- a/package/src/common/dependencies/esbuild.ts
+++ b/package/src/common/dependencies/esbuild.ts
@@ -56,7 +56,7 @@ export function esBuild(version: string): Dependency {
           }
         } else {
           // verify that the binary is on PATH, but otherwise don't do anything
-          if (which(file) === undefined) {
+          if ((await which(file)) === undefined) {
             throw new Error(
               `${file} is not on PATH. Please install it and add it to PATH.`,
             );
diff --git a/package/src/common/dependencies/pandoc.ts b/package/src/common/dependencies/pandoc.ts
index 706d5775d07..41dc41d75c2 100644
--- a/package/src/common/dependencies/pandoc.ts
+++ b/package/src/common/dependencies/pandoc.ts
@@ -70,7 +70,7 @@ export function pandoc(version: string): Dependency {
           }
         } else {
           // verify that the binary is on PATH, but otherwise don't do anything
-          if (which(pandocBinary) === undefined) {
+          if ((await which(pandocBinary)) === undefined) {
             throw new Error(
               `${pandocBinary} is not on PATH. Please install it and add it to PATH.`,
             );
diff --git a/package/src/common/dependencies/typst-gather.ts b/package/src/common/dependencies/typst-gather.ts
index cf805e5a617..aca041b657e 100644
--- a/package/src/common/dependencies/typst-gather.ts
+++ b/package/src/common/dependencies/typst-gather.ts
@@ -28,7 +28,7 @@ export function typstGather(version: string): Dependency {
           Deno.renameSync(extractedPath, join(targetDir, file));
         } else {
           // verify that the binary is on PATH, but otherwise don't do anything
-          if (which(file) === undefined) {
+          if ((await which(file)) === undefined) {
             throw new Error(
               `${file} is not on PATH. Please install it and add it to PATH.`,
             );
diff --git a/package/src/common/dependencies/typst.ts b/package/src/common/dependencies/typst.ts
index 1538f8f0055..27a046a4519 100644
--- a/package/src/common/dependencies/typst.ts
+++ b/package/src/common/dependencies/typst.ts
@@ -45,7 +45,7 @@ export function typst(version: string ): Dependency {
           }
         } else {
           // verify that the binary is on PATH, but otherwise don't do anything
-          if (which(file) === undefined) {
+          if ((await which(file)) === undefined) {
             throw new Error(
               `${file} is not on PATH. Please install it and add it to PATH.`,
             );
diff --git a/src/command/dev-call/typst-gather/cmd.ts b/src/command/dev-call/typst-gather/cmd.ts
index abc51188b7d..4279f3c3575 100644
--- a/src/command/dev-call/typst-gather/cmd.ts
+++ b/src/command/dev-call/typst-gather/cmd.ts
@@ -40,10 +40,17 @@ export const typstGatherCommand = new Command()
     const typstGatherBinary = Deno.env.get("QUARTO_TYPST_GATHER") ||
       architectureToolsPath(binaryName);
     if (!existsSync(typstGatherBinary)) {
-      error(
-        `typst-gather binary not found.\n` +
-          "Run ./configure.sh to build and install it.",
-      );
+      error(`typst-gather binary not found at ${typstGatherBinary}.`);
+      if (Deno.env.get("QUARTO_TYPST_GATHER")) {
+        error(
+          "QUARTO_TYPST_GATHER is set but does not point to an existing file.",
+        );
+      } else {
+        error(
+          "Run ./configure.sh to download it, or set QUARTO_TYPST_GATHER to " +
+            "the path of a typst-gather binary.",
+        );
+      }
       Deno.exit(1);
     }
 
diff --git a/src/core/typst-gather.ts b/src/core/typst-gather.ts
index 8a4e9a45662..c50ca9700ad 100644
--- a/src/core/typst-gather.ts
+++ b/src/core/typst-gather.ts
@@ -37,8 +37,12 @@ export function typstGatherBinaryPath(): string {
 
   if (!existsSync(binary)) {
     throw new Error(
-      `typst-gather binary not found.\n` +
-        `Run ./configure.sh to build and install it.`,
+      `typst-gather binary not found at ${binary}.\n` +
+        (Deno.env.get("QUARTO_TYPST_GATHER")
+          ? `QUARTO_TYPST_GATHER is set but does not point to an existing file.`
+          : `Reinstall Quarto to restore the bundled binary, or set ` +
+            `QUARTO_TYPST_GATHER to the path of a typst-gather binary.\n` +
+            `In a Quarto source checkout, run ./configure.sh to download it.`),
     );
   }