diff --git a/src/jrd/gds.cpp b/src/jrd/gds.cpp
index 69e318a121..51ea40fdd4 100644
--- a/src/jrd/gds.cpp
+++ b/src/jrd/gds.cpp
@@ -3588,14 +3588,22 @@ static void safe_concat_path(TEXT *resultString, const TEXT *appendString)
  *
  **************************************/
 	size_t len = strlen(resultString);
-	if (resultString[len - 1] != PathUtils::dir_sep && len < MAXPATHLEN - 1) {
+	if (resultString[len - 1] != PathUtils::dir_sep && len < MAXPATHLEN - 1) 
+	{
 		resultString[len++] = PathUtils::dir_sep;
 		resultString[len] = 0;
 	}
+
 	size_t alen = strlen(appendString);
 	if (len + alen > MAXPATHLEN - 1)
+	{
 		alen = MAXPATHLEN - 1 - len;
-	fb_assert(len + alen <= MAXPATHLEN);
+	}
+
+	fb_assert(len < MAXPATHLEN);
+	fb_assert(alen < MAXPATHLEN);
+	fb_assert(len + alen < MAXPATHLEN);
+
 	memcpy(&resultString[len], appendString, alen);
 	resultString[len + alen] = 0;
 }