diff --git a/src/add-ons/kernel/file_systems/ext2/Volume.cpp b/src/add-ons/kernel/file_systems/ext2/Volume.cpp
index dff0520458..cce2cba784 100644
--- a/src/add-ons/kernel/file_systems/ext2/Volume.cpp
+++ b/src/add-ons/kernel/file_systems/ext2/Volume.cpp
@@ -168,6 +168,16 @@ Volume::Mount(const char* deviceName, uint32 flags)
 	if (!_VerifySuperBlock())
 		return B_ERROR;
 
+	if ((fSuperBlock.State() & EXT2_FS_STATE_VALID) == 0
+		|| (fSuperBlock.State() & EXT2_FS_STATE_ERROR) != 0) {
+		if (!IsReadOnly()) {
+			FATAL("Volume::Mount(): can't mount R/W, volume not clean\n");
+			return B_NOT_ALLOWED;
+		} else {
+			FATAL("Volume::Mount(): warning: volume not clean\n");
+		}
+	}
+
 	// initialize short hands to the superblock (to save byte swapping)
 	fBlockShift = fSuperBlock.BlockShift();
 	if (fBlockShift < 10 || fBlockShift > 16)
diff --git a/src/add-ons/kernel/file_systems/ext2/ext2.h b/src/add-ons/kernel/file_systems/ext2/ext2.h
index 3b4e4f0a06..a307bb8ed6 100644
--- a/src/add-ons/kernel/file_systems/ext2/ext2.h
+++ b/src/add-ons/kernel/file_systems/ext2/ext2.h
@@ -171,9 +171,9 @@ struct ext2_super_block {
 
 #define EXT2_MAX_REVISION		EXT2_DYNAMIC_REVISION
 
-#define EXT2_FS_STATE_VALID		1	// File system was cleanly unmounted
-#define EXT2_FS_STATE_ERROR		2	// File system has errors
-#define EXT2_FS_STATE_ORPHAN	3	// Orphans are being recovered
+#define EXT2_FS_STATE_VALID		0x1	// File system was cleanly unmounted
+#define EXT2_FS_STATE_ERROR		0x2	// File system has errors
+#define EXT2_FS_STATE_ORPHAN	0x4	// Orphans are being recovered
 
 // compatible features
 #define EXT2_FEATURE_DIRECTORY_PREALLOCATION	0x0001