diff --git a/libs/main/types/pibytearray.cpp b/libs/main/types/pibytearray.cpp
index f3c5359d..7d064d40 100644
--- a/libs/main/types/pibytearray.cpp
+++ b/libs/main/types/pibytearray.cpp
@@ -198,10 +198,11 @@ PIByteArray PIByteArray::fromBase64(const PIByteArray & base64) {
 	base64HelpStruct hs;
 	PIByteArray ret;
 	const int sz = base64.size_s();
-	int ind      = -1;
+	if (sz < 4) return PIByteArray();
+	int ind = -1;
 	uchar t[4];
 	ret.resize(sz / 4 * 3);
-	for (int i = 0; i < sz; i += 4) {
+	for (int i = 0; i < sz / 4 * 4; i += 4) {
 		hs.setAscii(base64.data(i));
 		hs.getBytes(t);
 		ret[++ind] = (t[0]);