diff --git a/src/libfetchers/input-accessor.cc b/src/libfetchers/input-accessor.cc
index fb26ced4b..7e4c46cff 100644
--- a/src/libfetchers/input-accessor.cc
+++ b/src/libfetchers/input-accessor.cc
@@ -289,10 +289,14 @@ SourcePath SourcePath::resolveSymlinks() const
 {
     CanonPath res("/");
 
+    int linksAllowed = 1024;
+
     for (auto & component : path) {
         res.push(component);
         while (true) {
             if (auto st = accessor.maybeLstat(res)) {
+                if (!linksAllowed--)
+                    throw Error("infinite symlink recursion in path '%s'", path);
                 if (st->type != InputAccessor::tSymlink) break;
                 auto target = accessor.readLink(res);
                 if (hasPrefix(target, "/"))
diff --git a/tests/eval.sh b/tests/eval.sh
index d74976019..ffae08a6a 100644
--- a/tests/eval.sh
+++ b/tests/eval.sh
@@ -29,3 +29,7 @@ nix-instantiate --eval -E 'assert 1 + 2 == 3; true'
 [[ $(nix-instantiate -A attr --eval "./eval.nix") == '{ foo = "bar"; }' ]]
 [[ $(nix-instantiate -A attr --eval --json "./eval.nix") == '{"foo":"bar"}' ]]
 [[ $(nix-instantiate -A int --eval - < "./eval.nix") == 123 ]]
+
+# Check that symlink cycles don't cause a hang.
+ln -sfn cycle.nix $TEST_ROOT/cycle.nix
+(! nix eval --file $TEST_ROOT/cycle.nix)