diff --git a/pkgs/tools/text/kramdown-rfc2629/Gemfile.lock b/pkgs/tools/text/kramdown-rfc2629/Gemfile.lock
index b50dc2fdbca..feab5cddf99 100644
--- a/pkgs/tools/text/kramdown-rfc2629/Gemfile.lock
+++ b/pkgs/tools/text/kramdown-rfc2629/Gemfile.lock
@@ -2,9 +2,11 @@ GEM
   remote: https://rubygems.org/
   specs:
     certified (1.0.0)
+    json_pure (2.5.1)
     kramdown (1.17.0)
-    kramdown-rfc2629 (1.2.13)
+    kramdown-rfc2629 (1.3.37)
       certified (~> 1.0)
+      json_pure (~> 2.0)
       kramdown (~> 1.17.0)
 
 PLATFORMS
diff --git a/pkgs/tools/text/kramdown-rfc2629/gemset.nix b/pkgs/tools/text/kramdown-rfc2629/gemset.nix
index bf0cf130c42..f0b6c39a359 100644
--- a/pkgs/tools/text/kramdown-rfc2629/gemset.nix
+++ b/pkgs/tools/text/kramdown-rfc2629/gemset.nix
@@ -9,6 +9,16 @@
     };
     version = "1.0.0";
   };
+  json_pure = {
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "030hmc268wchqsccbjk41hvbyg99krpa72i3q0y3wwqzfh8hi736";
+      type = "gem";
+    };
+    version = "2.5.1";
+  };
   kramdown = {
     groups = ["default"];
     platforms = [];
@@ -20,14 +30,14 @@
     version = "1.17.0";
   };
   kramdown-rfc2629 = {
-    dependencies = ["certified" "kramdown"];
+    dependencies = ["certified" "json_pure" "kramdown"];
     groups = ["default"];
     platforms = [];
     source = {
       remotes = ["https://rubygems.org"];
-      sha256 = "0s53m46qlcdakik0czvx0p41mk46l9l36331cps8gpf364wf3l9d";
+      sha256 = "16m08q5bgib3i54bb9p3inrxb1xksiybs9zj1rnncq492gcqqv4j";
       type = "gem";
     };
-    version = "1.2.13";
+    version = "1.3.37";
   };
 }