diff --git a/src/c4group/CStdFile.cpp b/src/c4group/CStdFile.cpp
index c7dccbcb6..1d9912cdf 100644
--- a/src/c4group/CStdFile.cpp
+++ b/src/c4group/CStdFile.cpp
@@ -126,6 +126,14 @@ bool CStdFile::Open(const char *szFilename, bool fCompressed)
 
 		if(fd == -1) return false;
 		if (!(hgzFile = c4_gzdopen(fd,"rb"))) { close(fd); return false; }
+
+		/* Reject uncompressed files */
+		if(c4_gzdirect(hgzFile))
+		{
+			c4_gzclose(hgzFile);
+			hgzFile = NULL;
+			return false;
+		}
 	}
 	else
 	{ 
diff --git a/src/zlib/gzio.c b/src/zlib/gzio.c
index 4681112f3..b9985423a 100644
--- a/src/zlib/gzio.c
+++ b/src/zlib/gzio.c
@@ -208,13 +208,6 @@ local gzFile gz_open (path, mode, fd)
         s->start = ftell(s->file) - s->stream.avail_in;
     }
 
-    /* Reject uncompressed files */
-    if (s->transparent)
-		{
-        gzclose( (gzFile)s );
-        return (gzFile)Z_NULL;
-    }
-
     return (gzFile)s;
 }