diff --git a/vlib/builtin/map.v b/vlib/builtin/map.v
index 47dbba29ba..c92ab3b1b3 100644
--- a/vlib/builtin/map.v
+++ b/vlib/builtin/map.v
@@ -175,14 +175,16 @@ fn (mut d DenseArray) zeros_to_end() {
 		if d.has_index(i) {
 			// swap (TODO: optimize)
 			unsafe {
-				// Swap keys
-				C.memcpy(tmp_key, d.key(count), d.key_bytes)
-				C.memcpy(d.key(count), d.key(i), d.key_bytes)
-				C.memcpy(d.key(i), tmp_key, d.key_bytes)
-				// Swap values
-				C.memcpy(tmp_value, d.value(count), d.value_bytes)
-				C.memcpy(d.value(count), d.value(i), d.value_bytes)
-				C.memcpy(d.value(i), tmp_value, d.value_bytes)
+				if count != i {
+					// Swap keys
+					C.memcpy(tmp_key, d.key(count), d.key_bytes)
+					C.memcpy(d.key(count), d.key(i), d.key_bytes)
+					C.memcpy(d.key(i), tmp_key, d.key_bytes)
+					// Swap values
+					C.memcpy(tmp_value, d.value(count), d.value_bytes)
+					C.memcpy(d.value(count), d.value(i), d.value_bytes)
+					C.memcpy(d.value(i), tmp_value, d.value_bytes)
+				}
 			}
 			count++
 		}