diff --git a/src/protocols/rdp/guac_rdpdr/rdpdr_fs.c b/src/protocols/rdp/guac_rdpdr/rdpdr_fs.c
index 58fc7eb4..e5069424 100644
--- a/src/protocols/rdp/guac_rdpdr/rdpdr_fs.c
+++ b/src/protocols/rdp/guac_rdpdr/rdpdr_fs.c
@@ -422,3 +422,16 @@ int guac_rdpdr_fs_convert_path(const char* parent, const char* rel_path, char* a
 
 }
 
+guac_rdpdr_fs_file* guac_rdpdr_fs_get_file(guac_rdpdr_device* device,
+        int file_id) {
+
+    /* Validate ID */
+    guac_rdpdr_fs_data* data = (guac_rdpdr_fs_data*) device->data;
+    if (file_id < 0 || file_id >= GUAC_RDPDR_FS_MAX_FILES)
+        return NULL;
+
+    /* Return file at given ID */
+    return &(data->files[file_id]);
+
+}
+
diff --git a/src/protocols/rdp/guac_rdpdr/rdpdr_fs.h b/src/protocols/rdp/guac_rdpdr/rdpdr_fs.h
index bc7b025a..23d7d8a7 100644
--- a/src/protocols/rdp/guac_rdpdr/rdpdr_fs.h
+++ b/src/protocols/rdp/guac_rdpdr/rdpdr_fs.h
@@ -258,5 +258,11 @@ int guac_rdpdr_fs_convert_path(const char* parent, const char* rel_path, char* a
  */
 const char* guac_rdpdr_fs_read_dir(guac_rdpdr_device* device, int file_id);
 
+/**
+ * Returns the file having the given ID, or NULL if no such file exists.
+ */
+guac_rdpdr_fs_file* guac_rdpdr_fs_get_file(guac_rdpdr_device* device,
+        int file_id);
+
 #endif
 
diff --git a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages.c b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages.c
index bfa3f673..270ee173 100644
--- a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages.c
+++ b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages.c
@@ -292,13 +292,17 @@ void guac_rdpdr_fs_process_query_directory(guac_rdpdr_device* device, wStream* i
 
     wStream* output_stream;
 
-    guac_rdpdr_fs_data* data = (guac_rdpdr_fs_data*) device->data;
-    guac_rdpdr_fs_file* file = &(data->files[file_id]);
+    guac_rdpdr_fs_file* file;
     int fs_information_class, initial_query;
     int path_length;
 
     const char* entry_name;
 
+    /* Get file */
+    file = guac_rdpdr_fs_get_file(device, file_id);
+    if (file == NULL)
+        return;
+
     /* Read main header */
     Stream_Read_UINT32(input_stream, fs_information_class);
     Stream_Read_UINT8(input_stream,  initial_query);
diff --git a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_dir_info.c b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_dir_info.c
index c03daa41..41a56cda 100644
--- a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_dir_info.c
+++ b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_dir_info.c
@@ -63,8 +63,7 @@ void guac_rdpdr_fs_process_query_full_directory_info(guac_rdpdr_device* device,
 void guac_rdpdr_fs_process_query_both_directory_info(guac_rdpdr_device* device,
         const char* entry_name, int file_id, int completion_id) {
 
-    guac_rdpdr_fs_data* data = (guac_rdpdr_fs_data*) device->data;
-    guac_rdpdr_fs_file* file = &(data->files[file_id]);
+    guac_rdpdr_fs_file* file;
 
     wStream* output_stream = Stream_New(NULL, 256);
     int length = guac_utf8_strlen(entry_name);
@@ -73,6 +72,11 @@ void guac_rdpdr_fs_process_query_both_directory_info(guac_rdpdr_device* device,
     unsigned char utf16_entry_name[256];
     guac_rdp_utf8_to_utf16((const unsigned char*) entry_name, (char*) utf16_entry_name, length);
 
+    /* Get file */
+    file = guac_rdpdr_fs_get_file(device, file_id);
+    if (file == NULL)
+        return;
+
     /* Write header */
     Stream_Write_UINT16(output_stream, RDPDR_CTYP_CORE);
     Stream_Write_UINT16(output_stream, PAKID_CORE_DEVICE_IOCOMPLETION);
diff --git a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_file_info.c b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_file_info.c
index 30da8507..876f442c 100644
--- a/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_file_info.c
+++ b/src/protocols/rdp/guac_rdpdr/rdpdr_fs_messages_file_info.c
@@ -56,8 +56,12 @@ void guac_rdpdr_fs_process_query_basic_info(guac_rdpdr_device* device, wStream*
         int file_id, int completion_id) {
 
     wStream* output_stream = Stream_New(NULL, 60);
-    guac_rdpdr_fs_data* data = (guac_rdpdr_fs_data*) device->data;
-    guac_rdpdr_fs_file* file = &(data->files[file_id]);
+    guac_rdpdr_fs_file* file;
+
+    /* Get file */
+    file = guac_rdpdr_fs_get_file(device, file_id);
+    if (file == NULL)
+        return;
 
     /* Write header */
     Stream_Write_UINT16(output_stream, RDPDR_CTYP_CORE);
@@ -85,10 +89,14 @@ void guac_rdpdr_fs_process_query_standard_info(guac_rdpdr_device* device, wStrea
         int file_id, int completion_id) {
 
     wStream* output_stream = Stream_New(NULL, 60);
-    guac_rdpdr_fs_data* data = (guac_rdpdr_fs_data*) device->data;
-    guac_rdpdr_fs_file* file = &(data->files[file_id]);
-
+    guac_rdpdr_fs_file* file;
     BOOL is_directory = FALSE;
+
+    /* Get file */
+    file = guac_rdpdr_fs_get_file(device, file_id);
+    if (file == NULL)
+        return;
+
     if (file->attributes & FILE_ATTRIBUTE_DIRECTORY)
         is_directory = TRUE;