diff --git a/src/insets/InsetHyperlink.cpp b/src/insets/InsetHyperlink.cpp
index aae07ce0da..93dbaa94c5 100644
--- a/src/insets/InsetHyperlink.cpp
+++ b/src/insets/InsetHyperlink.cpp
@@ -133,8 +133,8 @@ void InsetHyperlink::latex(otexstream & os,
 	if (!url.empty()) {
 		// Use URI/URL-style percent-encoded string (hexadecimal).
 		// We exclude some characters that must not be transformed
-		// in hrefs (% # / :) or that we need to treat manually (\).
-		url = to_percent_encoding(url, from_ascii("%#\\/:"));
+		// in hrefs (% # / : ? =) or that we need to treat manually (\).
+		url = to_percent_encoding(url, from_ascii("%#\\/:?="));
 		// We handle \ manually since \\ is valid
 		for (size_t i = 0, pos;
 			(pos = url.find('\\', i)) != string::npos;