diff --git a/src/uxnasm.c b/src/uxnasm.c
index 7c0f6c5..d7b2229 100644
--- a/src/uxnasm.c
+++ b/src/uxnasm.c
@@ -243,8 +243,13 @@ parse(char *w, FILE *f)
 		return error("Invalid token", w);
 	switch(w[0]) {
 	case '(': /* comment */
-		while(fscanf(f, "%63s", word) == 1)
-			if(word[0] == ')') break;
+		if(slen(w) != 1) fprintf(stderr, "-- Malformed comment: %s\n", w);
+		i = 1; /* track nested comment depth */
+		while(fscanf(f, "%63s", word) == 1) {
+			if(slen(word) != 1) continue;
+			else if(word[0] == '(') i++;
+			else if(word[0] == ')' && --i < 1) break;
+		}
 		break;
 	case '~': /* include */
 		if(!doinclude(w + 1))