diff --git a/src/system/kernel/cache/block_cache.cpp b/src/system/kernel/cache/block_cache.cpp
index c47cd99380..061de92eb2 100644
--- a/src/system/kernel/cache/block_cache.cpp
+++ b/src/system/kernel/cache/block_cache.cpp
@@ -30,7 +30,7 @@
 //	3) dirty blocks are only written back if asked for
 //	4) blocks are never removed yet
 
-#define TRACE_BLOCK_CACHE
+//#define TRACE_BLOCK_CACHE
 #ifdef TRACE_BLOCK_CACHE
 #	define TRACE(x)	dprintf x
 #else
@@ -793,12 +793,6 @@ cache_abort_sub_transaction(void *_cache, int32 id)
 	for (; block != NULL; block = next) {
 		next = block->transaction_next;
 
-		if (block->original == NULL) {
-			// an unchanged block in the transaction?
-panic("unchanged block in transaction!");
-			continue;
-		}
-
 		if (block->parent_data != block->data) {
 			// the block has been changed and must be restored
 			TRACE(("cache_abort_sub_transaction(id = %ld): restored contents of block %Ld\n",
@@ -836,12 +830,6 @@ cache_start_sub_transaction(void *_cache, int32 id)
 	for (; block != NULL; block = next) {
 		next = block->transaction_next;
 
-		if (block->original == NULL) {
-			// an unchanged block in the transaction?
-panic("unchanged block in transaction!");
-			continue;
-		}
-
 		if (transaction->has_sub_transaction && block->parent_data != block->data) {
 			// there already is an older sub transaction - we acknowledge
 			// its changes and move its blocks up to the parent
diff --git a/src/system/kernel/cache/file_cache.cpp b/src/system/kernel/cache/file_cache.cpp
index 4c53d3d3d9..793653d9dc 100644
--- a/src/system/kernel/cache/file_cache.cpp
+++ b/src/system/kernel/cache/file_cache.cpp
@@ -323,7 +323,7 @@ pages_io(file_cache_ref *ref, off_t offset, const iovec *vecs, size_t count,
 		//	a) also use this direct I/O for writes (otherwise, it would overwrite precious data)
 		//	b) panic if the term below is true (at least for writes)
 		if (size > fileVecs[0].length) {
-			dprintf("warning: device driver %p doesn't respect total length in read_pages() call!\n", ref->device);
+			//dprintf("warning: device driver %p doesn't respect total length in read_pages() call!\n", ref->device);
 			size = fileVecs[0].length;
 		}