diff --git a/src/sys/dirctl.c b/src/sys/dirctl.c
index 872aac37..33254544 100644
--- a/src/sys/dirctl.c
+++ b/src/sys/dirctl.c
@@ -865,6 +865,8 @@ NTSTATUS FspFsvolDirectoryControlPrepare(
     PVOID Address;
     PEPROCESS Process;
 
+    ASSERT(FspProcessBufferSizeMax >= Request->Req.QueryDirectory.Length);
+
     Result = FspProcessBufferAcquire(Request->Req.QueryDirectory.Length, &Cookie, &Address);
     if (!NT_SUCCESS(Result))
         return Result;
diff --git a/src/sys/driver.h b/src/sys/driver.h
index ebe29371..31948e7d 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -1127,7 +1127,7 @@ enum
     FspFsvolDeviceSecurityCacheCapacity = 100,
     FspFsvolDeviceSecurityCacheItemSizeMax = 4096,
     FspFsvolDeviceDirInfoCacheCapacity = 100,
-    FspFsvolDeviceDirInfoCacheItemSizeMax = FSP_FSCTL_ALIGN_UP(16384, PAGE_SIZE),
+    FspFsvolDeviceDirInfoCacheItemSizeMax = FSP_FSCTL_ALIGN_UP(FspProcessBufferSizeMax, PAGE_SIZE),
     FspFsvolDeviceStreamInfoCacheCapacity = 100,
     FspFsvolDeviceStreamInfoCacheItemSizeMax = FSP_FSCTL_ALIGN_UP(16384, PAGE_SIZE),
     FspFsvolDeviceEaCacheCapacity = 100,
diff --git a/tst/winfsp-tests/dirctl-test.c b/tst/winfsp-tests/dirctl-test.c
index 246e23ef..dc101d9c 100644
--- a/tst/winfsp-tests/dirctl-test.c
+++ b/tst/winfsp-tests/dirctl-test.c
@@ -46,7 +46,7 @@ static void querydir_dotest(ULONG Flags, PWSTR Prefix, ULONG FileInfoTimeout, UL
         ASSERT(Success);
     }
 
-    for (int j = 1; 100 >= j; j++)
+    for (int j = 1; 400 >= j; j++)
     {
         StringCbPrintfW(FilePath, sizeof FilePath, L"%s%s\\fileABCDEFGHIJKLMNOPQRSTUVXWYZfile%d",
             Prefix ? L"" : L"\\\\?\\GLOBALROOT", Prefix ? Prefix : memfs_volumename(memfs), j);
@@ -90,7 +90,7 @@ static void querydir_dotest(ULONG Flags, PWSTR Prefix, ULONG FileInfoTimeout, UL
         } while (FindNextFileW(Handle, &FindData));
         ASSERT(ERROR_NO_MORE_FILES == GetLastError());
 
-        ASSERT(110 == FileCount);
+        ASSERT(410 == FileCount);
 
         Success = FindClose(Handle);
         ASSERT(Success);
@@ -194,8 +194,8 @@ static void querydir_dotest(ULONG Flags, PWSTR Prefix, ULONG FileInfoTimeout, UL
     } while (FindNextFileW(Handle, &FindData));
     ASSERT(ERROR_NO_MORE_FILES == GetLastError());
 
-    ASSERT(100 == FileCount);
-    ASSERT(101 * 100 / 2 == FileTotal);
+    ASSERT(400 == FileCount);
+    ASSERT(401 * 400 / 2 == FileTotal);
 
     Success = FindClose(Handle);
     ASSERT(Success);
@@ -224,7 +224,7 @@ static void querydir_dotest(ULONG Flags, PWSTR Prefix, ULONG FileInfoTimeout, UL
         ASSERT(Success);
     }
 
-    for (int j = 1; 100 >= j; j++)
+    for (int j = 1; 400 >= j; j++)
     {
         StringCbPrintfW(FilePath, sizeof FilePath, L"%s%s\\fileABCDEFGHIJKLMNOPQRSTUVXWYZfile%d",
             Prefix ? L"" : L"\\\\?\\GLOBALROOT", Prefix ? Prefix : memfs_volumename(memfs), j);