diff --git a/src/expand.c b/src/expand.c
index 947bee0..acb6906 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -2651,9 +2651,11 @@
 	avrule->line = source_rule->line;
 	avrule->flags = source_rule->flags;
 	avrule->source_line = source_rule->source_line;
-	avrule->source_filename = strdup(source_rule->source_filename);
-	if (!avrule->source_filename)
-		goto err;
+	if (source_rule->source_filename) {
+		avrule->source_filename = strdup(source_rule->source_filename);
+		if (!avrule->source_filename)
+			goto err;
+	}
 
 	if (ebitmap_cpy(&avrule->stypes.types, &stypes))
 		goto err;
diff --git a/src/link.c b/src/link.c
index ca497a7..c8c510a 100644
--- a/src/link.c
+++ b/src/link.c
@@ -1326,9 +1326,11 @@
 		}
 		new_rule->line = cur->line;
 		new_rule->source_line = cur->source_line;
-		new_rule->source_filename = strdup(cur->source_filename);
-		if (!new_rule->source_filename)
-			goto cleanup;
+		if (cur->source_filename) {
+			new_rule->source_filename = strdup(cur->source_filename);
+			if (!new_rule->source_filename)
+				goto cleanup;
+		}
 
 		cur = cur->next;