diff --git a/src/renumber.c b/src/renumber.c
index 952e8db..54f5aec 100644
--- a/src/renumber.c
+++ b/src/renumber.c
@@ -374,8 +374,10 @@ akerr_ErrorContext *akbasic_renumber(akbasic_Runtime *obj, int64_t newstart, int
 	 * of running it over source that arrived without any.
 	 */
 	obj->renumber_line.numbered = true;
-	PASS(errctx, aksl_memcpy(&obj->source[i], &obj->renumber_line,
-				 sizeof(obj->source[i])));
+	PASS(errctx, aksl_strncpy(obj->source[i].code, AKBASIC_MAX_LINE_LENGTH,
+				 obj->renumber_line.code, AKBASIC_MAX_LINE_LENGTH));
+	obj->source[i].lineno = obj->renumber_line.lineno;
+	obj->source[i].numbered = obj->renumber_line.numbered;
     }
 
     /* Move the already-rewritten lines in place. The map is a partial
@@ -389,34 +391,47 @@ akerr_ErrorContext *akbasic_renumber(akbasic_Runtime *obj, int64_t newstart, int
 	if ( map[i] < 0 || obj->renumber_visited[i] ) {
 	    continue;
 	}
-	PASS(errctx, aksl_memcpy(&displaced, &obj->source[i], sizeof(displaced)));
+	PASS(errctx, aksl_strncpy(displaced.code, AKBASIC_MAX_LINE_LENGTH,
+				 obj->source[i].code, AKBASIC_MAX_LINE_LENGTH));
+	displaced.lineno = obj->source[i].lineno;
+	displaced.numbered = obj->source[i].numbered;
 	for ( ;; ) {
 	    int64_t destination = map[current];
 
 	    obj->renumber_visited[current] = 1;
 	    if ( destination == i ) {
 		displaced.lineno = destination;
-		PASS(errctx, aksl_memcpy(&obj->source[destination], &displaced,
-					 sizeof(displaced)));
+		PASS(errctx, aksl_strncpy(obj->source[destination].code, AKBASIC_MAX_LINE_LENGTH,
+					 displaced.code, AKBASIC_MAX_LINE_LENGTH));
+		obj->source[destination].lineno = displaced.lineno;
+		obj->source[destination].numbered = displaced.numbered;
 		break;
 	    }
 	    if ( map[destination] < 0 ) {
 		displaced.lineno = destination;
-		PASS(errctx, aksl_memcpy(&obj->source[destination], &displaced,
-					 sizeof(displaced)));
+		PASS(errctx, aksl_strncpy(obj->source[destination].code, AKBASIC_MAX_LINE_LENGTH,
+					 displaced.code, AKBASIC_MAX_LINE_LENGTH));
+		obj->source[destination].lineno = displaced.lineno;
+		obj->source[destination].numbered = displaced.numbered;
 		PASS(errctx, aksl_memset(&obj->source[current], 0,
 					 sizeof(obj->source[current])));
 		break;
 	    }
-	    PASS(errctx, aksl_memcpy(&next_line, &obj->source[destination],
-				     sizeof(displaced)));
+	    PASS(errctx, aksl_strncpy(next_line.code, AKBASIC_MAX_LINE_LENGTH,
+				     obj->source[destination].code, AKBASIC_MAX_LINE_LENGTH));
+	    next_line.lineno = obj->source[destination].lineno;
+	    next_line.numbered = obj->source[destination].numbered;
 	    displaced.lineno = destination;
-	    PASS(errctx, aksl_memcpy(&obj->source[destination], &displaced,
-				     sizeof(obj->renumber_line)));
+	    PASS(errctx, aksl_strncpy(obj->source[destination].code, AKBASIC_MAX_LINE_LENGTH,
+				     displaced.code, AKBASIC_MAX_LINE_LENGTH));
+	    obj->source[destination].lineno = displaced.lineno;
+	    obj->source[destination].numbered = displaced.numbered;
 	    PASS(errctx, aksl_memset(&obj->source[current], 0,
 				     sizeof(obj->source[current])));
-	    PASS(errctx, aksl_memcpy(&displaced, &next_line,
-				     sizeof(displaced)));
+	    PASS(errctx, aksl_strncpy(displaced.code, AKBASIC_MAX_LINE_LENGTH,
+				     next_line.code, AKBASIC_MAX_LINE_LENGTH));
+	    displaced.lineno = next_line.lineno;
+	    displaced.numbered = next_line.numbered;
 	    current = destination;
 	}
     }