diff --git a/ethermess-backend.c b/ethermess-backend.c
index 812ddf1..a28677d 100644
--- a/ethermess-backend.c
+++ b/ethermess-backend.c
@@ -589,7 +589,7 @@ bool check_utf8(const unsigned char *data, size_t data_length, bool newline_allo
 			// Reject control characters
 			if (codepoint <= 0x1f) {
 				// C0 control character
-				if (!newline_allowed || codepoint == 0x0a) {
+				if (!newline_allowed || codepoint != 0x0a) {
 					return false;
 				}
 			} else if (0x80 <= codepoint && codepoint <= 0x9f) {