diff --git a/src/core/json/CMakeLists.txt b/src/core/json/CMakeLists.txt
index 1d96e489c..0e481e5b9 100644
--- a/src/core/json/CMakeLists.txt
+++ b/src/core/json/CMakeLists.txt
@@ -1,5 +1,5 @@
 sourcemeta_library(NAMESPACE sourcemeta PROJECT core NAME json
-  PRIVATE_HEADERS array.h error.h object.h value.h hash.h
+  PRIVATE_HEADERS array.h error.h object.h value.h hash.hh
   SOURCES grammar.h parser.h stringify.h json.cc json_value.cc)
 
 if(SOURCEMETA_CORE_INSTALL)
diff --git a/src/core/json/include/sourcemeta/core/json.h b/src/core/json/include/sourcemeta/core/json.h
index 0603ca35c..a3c835e32 100644
--- a/src/core/json/include/sourcemeta/core/json.h
+++ b/src/core/json/include/sourcemeta/core/json.h
@@ -5,7 +5,6 @@
 #include <sourcemeta/core/json_export.h>
 #endif
 
-#include <sourcemeta/core/json_hash.h>
 #include <sourcemeta/core/json_value.h>
 
 #include <cstdint>    // std::uint64_t
diff --git a/src/core/json/include/sourcemeta/core/json_hash.h b/src/core/json/include/sourcemeta/core/json_hash.hh
similarity index 100%
rename from src/core/json/include/sourcemeta/core/json_hash.h
rename to src/core/json/include/sourcemeta/core/json_hash.hh
diff --git a/src/core/json/include/sourcemeta/core/json_value.h b/src/core/json/include/sourcemeta/core/json_value.h
index 96b36dbc5..8ad935411 100644
--- a/src/core/json/include/sourcemeta/core/json_value.h
+++ b/src/core/json/include/sourcemeta/core/json_value.h
@@ -6,7 +6,7 @@
 #endif
 
 #include <sourcemeta/core/json_array.h>
-#include <sourcemeta/core/json_hash.h>
+#include <sourcemeta/core/json_hash.hh>
 #include <sourcemeta/core/json_object.h>
 
 #include <algorithm>        // std::any_of