diff --git a/block/bochs.c b/block/bochs.c
index 34892582e..fb83594db 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -116,11 +116,9 @@ static int bochs_open(BlockDriverState *bs, const char *filename, int flags)
     struct bochs_header bochs;
     struct bochs_header_v1 header_v1;
 
-    fd = open(filename, O_RDWR | O_BINARY);
+    fd = open(filename, O_RDONLY | O_BINARY);
     if (fd < 0) {
-        fd = open(filename, O_RDONLY | O_BINARY);
-        if (fd < 0)
-            return -1;
+        return -1;
     }
 
     bs->read_only = 1; // no write support yet
diff --git a/block/parallels.c b/block/parallels.c
index 63b67380a..41b3a7c9d 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -74,11 +74,9 @@ static int parallels_open(BlockDriverState *bs, const char *filename, int flags)
     int fd, i;
     struct parallels_header ph;
 
-    fd = open(filename, O_RDWR | O_BINARY | O_LARGEFILE);
+    fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
     if (fd < 0) {
-        fd = open(filename, O_RDONLY | O_BINARY | O_LARGEFILE);
-        if (fd < 0)
-            return -1;
+        return -1;
     }
 
     bs->read_only = 1; // no write support yet