diff --git a/docs/changes.txt b/docs/changes.txt
index a1694fc9a..879ba3e7e 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -29,6 +29,7 @@
 - UTF8-to-UTF16: Replaced naive UTF8 to UTF16 conversion with true conversion for RAR3, AES Crypt, MultiBit HD (scrypt) and Umbraco HMAC-SHA1
 - AES Crypt Plugin: Reduced max password length from 256 to 128 which improved performance by 22%
 - RAR3-p (Compressed): Fix workaround in unrar library in AES constant table generation to enable multi-threading support
+- CRC32: Prevent decompression of data used in CRC32 calculation on host. This leads to false negatives with TrueCrypt/VeraCrypt keyfiles
 
 ##
 ## Technical
diff --git a/include/filehandling.h b/include/filehandling.h
index 88e9dc9d5..390cc40e0 100644
--- a/include/filehandling.h
+++ b/include/filehandling.h
@@ -15,22 +15,23 @@
 int    _wopen       (const char *path, int oflag, ...);
 #endif
 
-bool   hc_fopen     (HCFILE *fp, const char *path, char *mode);
-int    hc_fscanf    (HCFILE *fp, const char *format, void *ptr);
-int    hc_fprintf   (HCFILE *fp, const char *format, ...);
-int    hc_vfprintf  (HCFILE *fp, const char *format, va_list ap);
-int    hc_fseek     (HCFILE *fp, off_t offset, int whence);
-void   hc_rewind    (HCFILE *fp);
-off_t  hc_ftell     (HCFILE *fp);
-int    hc_fgetc     (HCFILE *fp);
-int    hc_fileno    (HCFILE *fp);
-int    hc_feof      (HCFILE *fp);
-void   hc_fflush    (HCFILE *fp);
-void   hc_fclose    (HCFILE *fp);
-int    hc_fputc     (int c, HCFILE *fp);
-char  *hc_fgets     (char *buf, int len, HCFILE *fp);
-size_t hc_fwrite    (const void *ptr, size_t size, size_t nmemb, HCFILE *fp);
-size_t hc_fread     (void *ptr, size_t size, size_t nmemb, HCFILE *fp);
+bool   hc_fopen       (HCFILE *fp, const char *path, char *mode);
+bool   hc_fopen_nozip (HCFILE *fp, const char *path, char *mode);
+int    hc_fscanf      (HCFILE *fp, const char *format, void *ptr);
+int    hc_fprintf     (HCFILE *fp, const char *format, ...);
+int    hc_vfprintf    (HCFILE *fp, const char *format, va_list ap);
+int    hc_fseek       (HCFILE *fp, off_t offset, int whence);
+void   hc_rewind      (HCFILE *fp);
+off_t  hc_ftell       (HCFILE *fp);
+int    hc_fgetc       (HCFILE *fp);
+int    hc_fileno      (HCFILE *fp);
+int    hc_feof        (HCFILE *fp);
+void   hc_fflush      (HCFILE *fp);
+void   hc_fclose      (HCFILE *fp);
+int    hc_fputc       (int c, HCFILE *fp);
+char  *hc_fgets       (char *buf, int len, HCFILE *fp);
+size_t hc_fwrite      (const void *ptr, size_t size, size_t nmemb, HCFILE *fp);
+size_t hc_fread       (void *ptr, size_t size, size_t nmemb, HCFILE *fp);
 
 size_t fgetl        (HCFILE *fp, char *line_buf, const size_t line_sz);
 u64    count_lines  (HCFILE *fp);
diff --git a/src/cpu_crc32.c b/src/cpu_crc32.c
index 1da9094bc..8c426b609 100644
--- a/src/cpu_crc32.c
+++ b/src/cpu_crc32.c
@@ -94,7 +94,7 @@ int cpu_crc32 (const char *filename, u8 keytab[64])
 
   HCFILE fp;
 
-  hc_fopen (&fp, filename, "rb");
+  hc_fopen_nozip (&fp, filename, "rb");
 
   #define MAX_KEY_SIZE (1024 * 1024)
 
diff --git a/src/filehandling.c b/src/filehandling.c
index 43256943e..b7b05fe1c 100644
--- a/src/filehandling.c
+++ b/src/filehandling.c
@@ -113,6 +113,68 @@ bool hc_fopen (HCFILE *fp, const char *path, char *mode)
   return true;
 }
 
+bool hc_fopen_nozip (HCFILE *fp, const char *path, char *mode)
+{
+  if (path == NULL || mode == NULL) return false;
+
+  int oflag = -1;
+
+  int fmode = S_IRUSR|S_IWUSR;
+
+  if (strncmp (mode, "a", 1) == 0 || strncmp (mode, "ab", 2) == 0)
+  {
+    oflag = O_WRONLY | O_CREAT | O_APPEND;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "ab", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else if (strncmp (mode, "r", 1) == 0 || strncmp (mode, "rb", 2) == 0)
+  {
+    oflag = O_RDONLY;
+    fmode = -1;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "rb", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else if (strncmp (mode, "w", 1) == 0 || strncmp (mode, "wb", 2) == 0)
+  {
+    oflag = O_WRONLY | O_CREAT | O_TRUNC;
+
+    #if defined(MSDOS) || defined(OS2) || defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
+    if (strncmp (mode, "wb", 2) == 0) oflag |= O_BINARY;
+    #endif
+  }
+  else
+  {
+    // ADD more strncmp to handle more "mode"
+    return false;
+  }
+
+  fp->pfp = NULL;
+  fp->is_gzip = false;
+  fp->is_zip = false;
+
+  if (fmode == -1)
+  {
+    fp->fd = open (path, oflag);
+  }
+  else
+  {
+    fp->fd = open (path, oflag, fmode);
+  }
+
+  if (fp->fd == -1 && fp->is_zip == false) return false;
+
+  if ((fp->pfp = fdopen (fp->fd, mode)) == NULL)  return false;
+
+  fp->path = path;
+  fp->mode = mode;
+
+  return true;
+}
+
 size_t hc_fread (void *ptr, size_t size, size_t nmemb, HCFILE *fp)
 {
   size_t n = -1;