--- a/pre-process.c
+++ b/pre-process.c
@@ -2410,22 +2410,27 @@ static void do_preprocess(struct token **list)
 
 void init_include_path(void)
 {
-	char path[256];
-	char os[32];
-	int error;
-	struct utsname name;
-
-	error = uname(&name);
-	if (error)
-		return;
-
-	if (strcmp(name.sysname, "Linux") != 0)
-		return;
-	strcpy(os, "linux-gnu");
-
-	snprintf(path, sizeof(path), "/usr/include/%s-%s/",
-			name.machine, os);
-	add_pre_buffer("#add_system \"%s/\"\n", path);
+	add_pre_buffer("#add_system \"%s/\"\n", "@clang@");
+	add_pre_buffer("#add_system \"%s/\"\n", "@libc@");
+
+    bool collect = false;
+    char *nix_cflags = getenv("NIX_CFLAGS_COMPILE");
+    if (nix_cflags == NULL)
+        return;
+
+    for (
+        char *token = strtok(nix_cflags, " ");
+        token != NULL;
+        token = strtok(NULL, " ")
+    ) {
+        if (collect && *token == '/') {
+	        add_pre_buffer("#add_system \"%s/\"\n", token);
+            collect = false;
+            continue;
+        }
+        if (!strcmp(token, "-isystem"))
+            collect = true;
+    }
 }
 
 struct token * preprocess(struct token *token)