diff --git a/src/render.cpp b/src/render.cpp
index 97fa745..204931a 100644
--- a/src/render.cpp
+++ b/src/render.cpp
@@ -390,7 +390,8 @@ void update_and_render(Arena *arena, App_State &app, f32 delta_time_ms)
         b8 hover_display_grouped = !(app.user_input.key_state[KEY_ALT] & KEY_STATE_IS_DOWN);
         Sec_Hover_Info hover_info = get_section_hover_info(scratch.arena, hovered_section, hovered_off - 1, 
                                                            app.inspected_file.mem, hover_display_grouped);
-        ImGui::TextColored(ImColor(0.5f, 0.5f, 0.5f), "(Hint: press Alt for single-field hover information)");
+        if (!app.rndata.header_is_compressed)
+          ImGui::TextColored(ImColor(0.5f, 0.5f, 0.5f), "(Hint: press Alt for single-field hover information)");
         imgui_render_string_tree(scratch.arena, hover_info.desc->head);
         app.viewer.hovered_range = hover_info.rng;
       } else {
diff --git a/src/rntuple.cpp b/src/rntuple.cpp
index 1b61b5b..f484a08 100644
--- a/src/rntuple.cpp
+++ b/src/rntuple.cpp
@@ -434,6 +434,7 @@ RNTuple_Data get_rntuple_data(Arena *arena, const Inspected_File &file, String8
     rndata.version.patch = file_info.anchor.fVersionPatch;
     rndata.rng_header.start = file_info.anchor.fSeekHeader;
     rndata.rng_header.len = file_info.anchor.fNBytesHeader;
+    rndata.header_is_compressed = file_info.anchor.fNBytesHeader != file_info.anchor.fLenHeader;
     rndata.rng_footer.start = file_info.anchor.fSeekFooter;
     rndata.rng_footer.len = file_info.anchor.fNBytesFooter;
     rndata.rng_anchor.start = file_info.anchor_seek;
diff --git a/src/rntuple.h b/src/rntuple.h
index 5ecb282..13e72a5 100644
--- a/src/rntuple.h
+++ b/src/rntuple.h
@@ -74,6 +74,8 @@ struct RNTuple_Data {
   Byte_Range rng_footer;
   Byte_Range rng_tkeys_list;
 
+  b8 header_is_compressed;
+
   Page_Info_Node *pages;
   u64 n_pages;
   // total number of elements of all pages