1 files changed, 5 insertions, 4 deletions

diff --git a/src/core/io_moves.h b/src/core/io_moves.h
index be43568..806887b 100644
--- a/src/core/io_moves.h
+++ b/src/core/io_moves.h
@@ -43,6 +43,7 @@ writemoves(uint8_t *m, int n, uint64_t buf_size, char *buf)
 {
         int i;
         uint64_t len;
+        int64_t written;
         const char *s;
         char *b;
 
@@ -51,16 +52,16 @@ writemoves(uint8_t *m, int n, uint64_t buf_size, char *buf)
                 return NISSY_ERROR_BUFFER_SIZE;
         }
 
-        for (i = 0, b = buf; i < n; i++, b++, buf_size--) {
+        for (i = 0, b = buf, written = 0; i < n; i++, b++, written++) {
                 s = movestr[m[i]];
                 len = strlen(s);
-                if (len >= buf_size) {
+                if (len + written >= buf_size) {
                         LOG("Error: the given buffer is too small for "
                              "writing the given moves.\n");
                         goto writemoves_error;
                 }
                 memcpy(b, s, len);
-                buf_size -= len;
+                written += len;
                 b += len;       
                 *b = ' ';
         }
@@ -69,7 +70,7 @@ writemoves(uint8_t *m, int n, uint64_t buf_size, char *buf)
                 b--; /* Remove last space */
         *b = '\0';
 
-        return buf_size;
+        return written;
 
 writemoves_error:
         *buf = '\0';