diff --git a/src/dict.c b/src/dict.c
index 2346f5be..26d0b1ff 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -505,6 +505,24 @@ void *dictFetchValue(dict *d, const void *key) {
     return he ? dictGetVal(he) : NULL;
 }
 
+/* A fingerprint is a 64 bit number that represents the state of the dictionary
+ * at a given time, it's just a few dict properties xored together.
+ * When an unsafe iterator is initialized, we get the dict fingerprint, and check
+ * the fingerprint again when the iterator is released.
+ * If the two fingerprints are different it means that the user of the iterator
+ * performed forbidden operations against the dictionary while iterating. */
+long long dictFingerprint(dict *d) {
+    long long fingerprint = 0;
+
+    fingerprint ^= (long long) d->ht[0].table;
+    fingerprint ^= (long long) d->ht[0].size;
+    fingerprint ^= (long long) d->ht[0].used;
+    fingerprint ^= (long long) d->ht[1].table;
+    fingerprint ^= (long long) d->ht[1].size;
+    fingerprint ^= (long long) d->ht[1].used;
+    return fingerprint;
+}
+
 dictIterator *dictGetIterator(dict *d)
 {
     dictIterator *iter = zmalloc(sizeof(*iter));
@@ -530,8 +548,12 @@ dictEntry *dictNext(dictIterator *iter)
     while (1) {
         if (iter->entry == NULL) {
             dictht *ht = &iter->d->ht[iter->table];
-            if (iter->safe && iter->index == -1 && iter->table == 0)
-                iter->d->iterators++;
+            if (iter->index == -1 && iter->table == 0) {
+                if (iter->safe)
+                    iter->d->iterators++;
+                else
+                    iter->fingerprint = dictFingerprint(iter->d);
+            }
             iter->index++;
             if (iter->index >= (signed) ht->size) {
                 if (dictIsRehashing(iter->d) && iter->table == 0) {
@@ -558,8 +580,12 @@ dictEntry *dictNext(dictIterator *iter)
 
 void dictReleaseIterator(dictIterator *iter)
 {
-    if (iter->safe && !(iter->index == -1 && iter->table == 0))
-        iter->d->iterators--;
+    if (!(iter->index == -1 && iter->table == 0)) {
+        if (iter->safe)
+            iter->d->iterators--;
+        else
+            assert(iter->fingerprint == dictFingerprint(iter->d));
+    }
     zfree(iter);
 }
 
diff --git a/src/dict.h b/src/dict.h
index 3a311f17..4d750ae8 100644
--- a/src/dict.h
+++ b/src/dict.h
@@ -88,6 +88,7 @@ typedef struct dictIterator {
     dict *d;
     int table, index, safe;
     dictEntry *entry, *nextEntry;
+    long long fingerprint; /* unsafe iterator fingerprint for misuse detection */
 } dictIterator;
 
 /* This is the initial size of every hash table */