diff --git a/src/nix/man-pages.cc b/src/nix/man-pages.cc
index a98a771cc..e9e89bb62 100644
--- a/src/nix/man-pages.cc
+++ b/src/nix/man-pages.cc
@@ -13,7 +13,7 @@ std::filesystem::path getNixManDir()
 void showManPage(const std::string & name)
 {
     restoreProcessContext();
-    setEnv("MANPATH", getNixManDir().c_str());
+    setEnv("MANPATH", (getNixManDir().string() + ":").c_str());
     execlp("man", "man", name.c_str(), nullptr);
     if (errno == ENOENT) {
         // Not SysError because we don't want to suffix the errno, aka No such file or directory.