diff --git a/inc/crn_decomp.h b/inc/crn_decomp.h
index c3269688..10db6000 100644
--- a/inc/crn_decomp.h
+++ b/inc/crn_decomp.h
@@ -2204,7 +2204,7 @@ const crn_header* crnd_get_header(const void* pData, uint32 data_size) {
   return &file_header;
 }
 
-bool crnd_validate_file(const void* pData, uint32 data_size, crn_file_info* pFile_info) {
+bool crnd_validate_header(const void* pData, uint32 data_size, crn_file_info* pFile_info) {
   if (pFile_info) {
     if (pFile_info->m_struct_size != sizeof(crn_file_info))
       return false;
@@ -2223,10 +2223,8 @@ bool crnd_validate_file(const void* pData, uint32 data_size, crn_file_info* pFil
   if (header_crc != pHeader->m_header_crc16)
     return false;
 
-  const uint32 data_crc = crc16((const uint8*)pData + pHeader->m_header_size, pHeader->m_data_size - pHeader->m_header_size);
-  if (data_crc != pHeader->m_data_crc16)
-    return false;
-
+  if (pHeader->m_data_size < pHeader->m_header_size)
+      return false;
   if ((pHeader->m_faces != 1) && (pHeader->m_faces != 6))
     return false;
   if ((pHeader->m_width < 1) || (pHeader->m_width > cCRNMaxLevelResolution))
@@ -2268,6 +2266,20 @@ bool crnd_validate_file(const void* pData, uint32 data_size, crn_file_info* pFil
   return true;
 }
 
+bool crnd_validate_file(const void* pData, uint32 data_size, crn_file_info* pFile_info) {
+  if (!crnd_validate_header(pData, data_size, pFile_info))
+    return false;
+
+  // was already validated by crnd_get_header
+  const crn_header* pHeader = static_cast<const crn_header*>(pData);
+
+  if (pHeader->m_data_size > data_size)
+      return false;
+
+  const uint32 data_crc = crc16((const uint8*)pData + pHeader->m_header_size, pHeader->m_data_size - pHeader->m_header_size);
+  return data_crc == pHeader->m_data_crc16;
+}
+
 bool crnd_get_texture_info(const void* pData, uint32 data_size, crn_texture_info* pInfo) {
   if ((!pData) || (data_size < sizeof(crn_header)) || (!pInfo))
     return false;
diff --git a/inc/crn_defs.h b/inc/crn_defs.h
index 1000cbbf..4b676d76 100644
--- a/inc/crn_defs.h
+++ b/inc/crn_defs.h
@@ -113,7 +113,14 @@ uint32 crnd_get_crn_format_bits_per_texel(crn_format fmt);
 // Returns the number of bytes per DXTn block (8 or 16).
 uint32 crnd_get_bytes_per_dxt_block(crn_format fmt);
 
-// Validates the entire file by checking the header and data CRC's.
+// Validates the file header, performing a CRC check on it and verifying that there is
+// e.g. a sane number of levels.
+// pData/data_size need only include the header, but may be the whole file.
+// The crn_file_info.m_struct_size field must be set before calling this function.
+bool crnd_validate_header(const void* pData, uint32 data_size, crn_file_info* pFile_info);
+
+// Validates the entire file by calling crnd_validate_header, then checking the data CRC
+// for the whole file.
 // This is not something you want to be doing much!
 // The crn_file_info.m_struct_size field must be set before calling this function.
 bool crnd_validate_file(const void* pData, uint32 data_size, crn_file_info* pFile_info);