diff --git a/src/db.c b/src/db.c
index 79d754d3b..48462ddb0 100644
--- a/src/db.c
+++ b/src/db.c
@@ -1871,8 +1871,9 @@ int64_t getAllKeySpecsFlags(struct redisCommand *cmd, int inv) {
  *                               found in other valid keyspecs. 
  */
 int getKeysUsingKeySpecs(struct redisCommand *cmd, robj **argv, int argc, int search_flags, getKeysResult *result) {
-    int j, i, k = 0, last, first, step;
+    int j, i, last, first, step;
     keyReference *keys;
+    result->numkeys = 0;
 
     for (j = 0; j < cmd->key_specs_num; j++) {
         keySpec *spec = cmd->key_specs + j;
@@ -1937,7 +1938,7 @@ int getKeysUsingKeySpecs(struct redisCommand *cmd, robj **argv, int argc, int se
         }
 
         int count = ((last - first)+1);
-        keys = getKeysPrepareResult(result, count);
+        keys = getKeysPrepareResult(result, result->numkeys + count);
 
         /* First or last is out of bounds, which indicates a syntax error */
         if (last >= argc || last < first || first >= argc) {
@@ -1958,8 +1959,9 @@ int getKeysUsingKeySpecs(struct redisCommand *cmd, robj **argv, int argc, int se
                     serverPanic("Redis built-in command declared keys positions not matching the arity requirements.");
                 }
             }
-            keys[k].pos = i;
-            keys[k++].flags = spec->flags;
+            keys[result->numkeys].pos = i;
+            keys[result->numkeys].flags = spec->flags;
+            result->numkeys++;
         }
 
         /* Handle incomplete specs (only after we added the current spec
@@ -1980,8 +1982,7 @@ invalid_spec:
         }
     }
 
-    result->numkeys = k;
-    return k;
+    return result->numkeys;
 }
 
 /* Return all the arguments that are keys in the command passed via argc / argv. 
diff --git a/tests/unit/introspection-2.tcl b/tests/unit/introspection-2.tcl
index 52a13edf7..89cb4b122 100644
--- a/tests/unit/introspection-2.tcl
+++ b/tests/unit/introspection-2.tcl
@@ -153,6 +153,21 @@ start_server {tags {"introspection"}} {
         assert_equal {key1 key2} [r command getkeys lcs key1 key2]
     }
 
+    test {COMMAND GETKEYS MORE THAN 256 KEYS} {
+        set all_keys [list]
+        set numkeys 260
+        for {set i 1} {$i <= $numkeys} {incr i} {
+            lappend all_keys "key$i"
+        }
+        set all_keys_with_target [linsert $all_keys 0 target]
+        # we are using ZUNIONSTORE command since in order to reproduce allocation of a new buffer in getKeysPrepareResult
+        # when numkeys in result > 0
+        # we need a command that the final number of keys is not known in the first call to getKeysPrepareResult
+        # before the fix in that case data of old buffer was not copied to the new result buffer
+        # causing all previous keys (numkeys) data to be uninitialize
+        assert_equal $all_keys_with_target [r command getkeys ZUNIONSTORE target $numkeys {*}$all_keys]
+    }
+
     test "COMMAND LIST syntax error" {
         assert_error "ERR syntax error*" {r command list bad_arg}
         assert_error "ERR syntax error*" {r command list filterby bad_arg}