diff --git a/pre-process.c b/pre-process.c
index 457685c0..006209ad 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -2410,32 +2410,27 @@ static void do_preprocess(struct token **list)
 
 void init_include_path(void)
 {
-	FILE *fp;
-	char path[256];
-	char arch[32];
-	char os[32];
-
-	fp = popen("/bin/uname -m", "r");
-	if (!fp)
-		return;
-	if (!fgets(arch, sizeof(arch) - 1, fp))
-		return;
-	pclose(fp);
-	if (arch[strlen(arch) - 1] == '\n')
-		arch[strlen(arch) - 1] = '\0';
-
-	fp = popen("/bin/uname -o", "r");
-	if (!fp)
-		return;
-	fgets(os, sizeof(os) - 1, fp);
-	pclose(fp);
-
-	if (strcmp(os, "GNU/Linux\n") != 0)
-		return;
-	strcpy(os, "linux-gnu");
-
-	snprintf(path, sizeof(path), "/usr/include/%s-%s/", arch, 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)