diff --git a/src/utils.c b/src/utils.c
index 2c553b4a8..6e8a543d1 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -131,15 +131,19 @@ void amountToString(const uint8_t *amount,
     uint8_t amount_len = strnlen(tmp_buffer, sizeof(tmp_buffer));
     uint8_t ticker_len = strnlen(ticker, MAX_TICKER_LEN);
 
-    memcpy(out_buffer, ticker, MIN(out_buffer_size, ticker_len));
-    if (ticker_len > 0) {
+    if (ticker_len > 0 && out_buffer_size > ticker_len + 1) {
+        memcpy(out_buffer, ticker, ticker_len);
         out_buffer[ticker_len++] = ' ';
     }
 
+    if (out_buffer_size < ticker_len) {
+        THROW(EXCEPTION_OVERFLOW);
+    }
+
     if (adjustDecimals(tmp_buffer,
                        amount_len,
                        out_buffer + ticker_len,
-                       out_buffer_size - ticker_len - 1,
+                       out_buffer_size - ticker_len,
                        decimals) == false) {
         THROW(EXCEPTION_OVERFLOW);
     }