diff --git a/src/utility/wide_string.cpp b/src/utility/wide_string.cpp
index 33702562..4453ec5b 100644
--- a/src/utility/wide_string.cpp
+++ b/src/utility/wide_string.cpp
@@ -34,9 +34,16 @@ std::wstring ToWString(std::string s)
 
 size_t wideLength(const std::wstring &ws)
 {
-	int len = wcswidth(ws.c_str(), -1);
-	assert(len >= 0);
-	return len;
+	size_t result = 0;
+	for (const auto &wc : ws)
+	{
+		int len = wcwidth(wc);
+		if (len < 0)
+			++result;
+		else
+			result += len;
+	}
+	return result;
 }
 
 void wideCut(std::wstring &ws, size_t max_length)