diff --git a/src/Message.cpp b/src/Message.cpp
index 7d9d243f..fee78e39 100644
--- a/src/Message.cpp
+++ b/src/Message.cpp
@@ -100,7 +100,7 @@ CString CMessage::ToString(unsigned int uFlags) const
 	for (unsigned int uIdx = 0; uIdx < uParams; ++uIdx) {
 		const CString& sParam = m_vsParams[uIdx];
 		sMessage += " ";
-		if (uIdx == uParams - 1 && (sParam.StartsWith(":") || sParam.Contains(" "))) {
+		if (uIdx == uParams - 1 && (sParam.empty() || sParam.StartsWith(":") || sParam.Contains(" "))) {
 			sMessage += ":";
 		}
 		sMessage += sParam;
diff --git a/test/MessageTest.cpp b/test/MessageTest.cpp
index 2d088c9e..7e1c93ed 100644
--- a/test/MessageTest.cpp
+++ b/test/MessageTest.cpp
@@ -43,6 +43,7 @@ TEST(MessageTest, ToString) {
 	EXPECT_EQ(":irc.znc.in CMD p1", CMessage(":irc.znc.in CMD p1").ToString());
 	EXPECT_EQ(":irc.znc.in CMD p1 p2", CMessage(":irc.znc.in CMD p1 p2").ToString());
 	EXPECT_EQ(":irc.znc.in CMD :p p p", CMessage(":irc.znc.in CMD :p p p").ToString());
+	EXPECT_EQ(":irc.znc.in CMD :", CMessage(":irc.znc.in CMD :").ToString());
 
 	EXPECT_EQ("CMD", CMessage(CNick(), "CMD", {}).ToString());
 	EXPECT_EQ("CMD p1", CMessage(CNick(), "CMD", {"p1"}).ToString());
@@ -53,6 +54,7 @@ TEST(MessageTest, ToString) {
 	EXPECT_EQ(":irc.znc.in CMD p1", CMessage(CNick(":irc.znc.in"), "CMD", {"p1"}).ToString());
 	EXPECT_EQ(":irc.znc.in CMD p1 p2", CMessage(CNick(":irc.znc.in"), "CMD", {"p1", "p2"}).ToString());
 	EXPECT_EQ(":irc.znc.in CMD :p p p", CMessage(CNick(":irc.znc.in"), "CMD", {"p p p"}).ToString());
+	EXPECT_EQ(":irc.znc.in CMD :", CMessage(CNick(":irc.znc.in"), "CMD", {""}).ToString());
 }
 
 TEST(MessageTest, FormatFlags) {