diff --git a/src/iperf_api.c b/src/iperf_api.c
index aa9c0ed..7e51d8c 100644
--- a/src/iperf_api.c
+++ b/src/iperf_api.c
@@ -418,8 +418,10 @@ mapped_v4_to_regular_v4(char *str)
     int prefix_len;
 
     prefix_len = strlen(prefix);
-    if (strncmp(str, prefix, prefix_len) == 0)
-        strcpy(str, str+prefix_len);
+    if (strncmp(str, prefix, prefix_len) == 0) {
+	int str_len = strlen(str);
+	memmove(str, str + prefix_len, str_len - prefix_len + 1);
+    }
 }
 
 void