diff --git a/cmdline/check.c b/cmdline/check.c
index d3941a9c..d5f52c44 100644
--- a/cmdline/check.c
+++ b/cmdline/check.c
@@ -501,7 +501,7 @@ static int repair(struct snapraid_state* state, int rehash, unsigned pos, unsign
 
 				/* try to fetch the old block using the old hash for CHG and DELETED blocks */
 			} else if ((block_state == BLOCK_STATE_CHG || block_state == BLOCK_STATE_DELETED)
-				&& hash_is_real(failed[j].block->hash)
+				&& hash_is_unique(failed[j].block->hash)
 				&& state_import_fetch(state, rehash, failed[j].block, buffer[failed[j].index]) == 0) {
 
 				/* note that from now the buffer is definitively lost */
diff --git a/cmdline/elem.h b/cmdline/elem.h
index a36a8286..48a05c15 100644
--- a/cmdline/elem.h
+++ b/cmdline/elem.h
@@ -536,11 +536,17 @@ int filter_content(tommy_list* contentlist, const char* path);
  * Check if the specified hash is invalid.
  *
  * An invalid hash is represented with all bytes at 0x00.
+ *
+ * If working with reduced hash lengths, this function always return 0.
  */
 static inline int hash_is_invalid(const unsigned char* hash)
 {
 	int i;
 
+	/* if the hash is reduced, we cannot grant that it's a specific kind of hash */
+	if (BLOCK_HASH_SIZE != HASH_MAX)
+		return 0;
+
 	for (i = 0; i < BLOCK_HASH_SIZE; ++i)
 		if (hash[i] != 0x00)
 			return 0;
@@ -552,11 +558,17 @@ static inline int hash_is_invalid(const unsigned char* hash)
  * Check if the specified hash represent the zero block.
  *
  * A zero hash is represented with all bytes at 0xFF.
+ *
+ * If working with reduced hash lengths, this function always return 0.
  */
 static inline int hash_is_zero(const unsigned char* hash)
 {
 	int i;
 
+	/* if the hash is reduced, we cannot grant that it's a specific kind of hash */
+	if (BLOCK_HASH_SIZE != HASH_MAX)
+		return 0;
+
 	for (i = 0; i < BLOCK_HASH_SIZE; ++i)
 		if (hash[i] != 0xFF)
 			return 0;
@@ -565,10 +577,16 @@ static inline int hash_is_zero(const unsigned char* hash)
 }
 
 /**
- * Check if the specified hash is a real hash.
+ * Check if the specified hash is uniquievocally repesenting the data.
+ *
+ * If working with reduced hash lengths, this function always return 0.
  */
-static inline int hash_is_real(const unsigned char* hash)
+static inline int hash_is_unique(const unsigned char* hash)
 {
+	/* if the hash is reduced, we cannot grant that it's a specific kind of hash */
+	if (BLOCK_HASH_SIZE != HASH_MAX)
+		return 0;
+
 	return !hash_is_zero(hash) && !hash_is_invalid(hash);
 }
 
diff --git a/cmdline/import.c b/cmdline/import.c
index 916f76ca..f00a0910 100644
--- a/cmdline/import.c
+++ b/cmdline/import.c
@@ -310,6 +310,14 @@ void state_import(struct snapraid_state* state, const char* dir)
 
 	msg_progress("Importing...\n");
 
+	/* if the hash is not full */
+	if (BLOCK_HASH_SIZE != HASH_MAX) {
+		/* LCOV_EXCL_START */
+		log_fatal("You cannot import files when using a reduced hash.\n");
+		exit(EXIT_FAILURE);
+		/* LCOV_EXCL_STOP */
+	}
+
 	/* add the final slash */
 	pathimport(path, sizeof(path), dir);
 	pathslash(path, sizeof(path));
diff --git a/cmdline/sync.c b/cmdline/sync.c
index 063c973b..57961a98 100644
--- a/cmdline/sync.c
+++ b/cmdline/sync.c
@@ -982,8 +982,8 @@ static int state_sync_process(struct snapraid_state* state, struct snapraid_pari
 					/* have "parity_needs_to_be_updated" already at 1 */
 					assert(block_state_get(block) == BLOCK_STATE_CHG);
 
-					/* if there is an hash */
-					if (hash_is_real(block->hash)) {
+					/* if the hash represents the data uniquievocally */
+					if (hash_is_unique(block->hash)) {
 						/* check if the hash is changed */
 						if (memcmp(hash, block->hash, BLOCK_HASH_SIZE) != 0) {
 							/* the block is different, and we must update parity */