diff --git a/libs/main/core/pistring.cpp b/libs/main/core/pistring.cpp
index 2e1e0c02..9b00c3f4 100644
--- a/libs/main/core/pistring.cpp
+++ b/libs/main/core/pistring.cpp
@@ -205,7 +205,7 @@ void PIString::appendFromChars(const char * c, int s, const char * codepage) {
 	UErrorCode e((UErrorCode)0);
 	UConverter * cc = ucnv_open(codepage, &e);
 	if (cc) {
-		if (s == -1) s = strlen(s);
+		if (s == -1) s = strlen(c);
 		enlarge(s);
 //		UChar * ucs = new UChar[s];
 //		memset(ucs, 0, s * sizeof(UChar));