diff --git a/src/log.c b/src/log.c
index 3d66e7a8c..2bb77c955 100644
--- a/src/log.c
+++ b/src/log.c
@@ -2235,7 +2235,15 @@ static inline char *_lf_text_len(char *dst, const char *src,
 			 * indefinite length text in cbor, because indefinite-length text
 			 * has to be made of multiple chunks of known size as per RFC8949...
 			 */
-			len = strnlen(src, len);
+			{
+				int _len;
+
+				/* strnlen(src, len) portable equivalent: */
+				for (_len = 0; _len < len && src[_len]; _len++)
+					;
+
+				len = _len;
+			}
 
 			ret = cbor_encode_text(&ctx->encode.cbor, dst, dst + size, src, len);
 			if (ret == NULL)