diff --git a/release/datafiles/userdef/userdef_default_theme.c b/release/datafiles/userdef/userdef_default_theme.c
index 19e9ab723fc..fed87c5018a 100644
--- a/release/datafiles/userdef/userdef_default_theme.c
+++ b/release/datafiles/userdef/userdef_default_theme.c
@@ -245,6 +245,7 @@ const bTheme U_theme_default = {
     .icon_shading = RGBA(0xcc6670ff),
     .icon_folder = RGBA(0xccad63ff),
     .panel_roundness = 0.4f,
+    .popup_panel_sub_back = RGBA(0x41403D1E),
   },
   .space_properties = {
     .back = RGBA(0x30303000),
diff --git a/scripts/startup/bl_ui/space_userpref.py b/scripts/startup/bl_ui/space_userpref.py
index a33892ace51..1a3f98bd4d0 100644
--- a/scripts/startup/bl_ui/space_userpref.py
+++ b/scripts/startup/bl_ui/space_userpref.py
@@ -1010,6 +1010,7 @@ class USERPREF_PT_theme_interface_styles(ThemePanel, CenterAlignMixIn, Panel):
         col.prop(ui, "editor_outline")
         col.prop(ui, "widget_emboss")
         col.prop(ui, "panel_roundness")
+        col.prop(ui, "popup_panel_sub_back")
 
 
 class USERPREF_PT_theme_interface_transparent_checker(ThemePanel, CenterAlignMixIn, Panel):
diff --git a/source/blender/blenkernel/BKE_blender_version.h b/source/blender/blenkernel/BKE_blender_version.h
index 2100ed68660..0d4bdb35ee0 100644
--- a/source/blender/blenkernel/BKE_blender_version.h
+++ b/source/blender/blenkernel/BKE_blender_version.h
@@ -29,7 +29,7 @@ extern "C" {
 
 /* Blender file format version. */
 #define BLENDER_FILE_VERSION BLENDER_VERSION
-#define BLENDER_FILE_SUBVERSION 12
+#define BLENDER_FILE_SUBVERSION 13
 
 /* Minimum Blender version that supports reading file written with the current
  * version. Older Blender versions will test this and cancel loading the file, showing a warning to
diff --git a/source/blender/blenloader/intern/versioning_userdef.cc b/source/blender/blenloader/intern/versioning_userdef.cc
index 63d2a158083..1a3528fe8c7 100644
--- a/source/blender/blenloader/intern/versioning_userdef.cc
+++ b/source/blender/blenloader/intern/versioning_userdef.cc
@@ -140,6 +140,10 @@ static void do_versions_theme(const UserDef *userdef, bTheme *btheme)
     FROM_DEFAULT_V4_UCHAR(space_view3d.face_mode_select);
   }
 
+  if (!USER_VERSION_ATLEAST(402, 13)) {
+    FROM_DEFAULT_V4_UCHAR(tui.popup_panel_sub_back);
+  }
+
   /**
    * Always bump subversion in BKE_blender_version.h when adding versioning
    * code here, and wrap it inside a USER_VERSION_ATLEAST check.
diff --git a/source/blender/editors/include/UI_resources.hh b/source/blender/editors/include/UI_resources.hh
index 437533e444e..9faee70f0e1 100644
--- a/source/blender/editors/include/UI_resources.hh
+++ b/source/blender/editors/include/UI_resources.hh
@@ -354,6 +354,8 @@ enum ThemeColorID {
 
   TH_EDGE_BEVEL,
   TH_VERTEX_BEVEL,
+
+  TH_POPUP_PANEL_SUB_BACK,
 };
 
 /* Specific defines per space should have higher define values. */
diff --git a/source/blender/editors/interface/interface.cc b/source/blender/editors/interface/interface.cc
index 853cf97ed81..e5347500294 100644
--- a/source/blender/editors/interface/interface.cc
+++ b/source/blender/editors/interface/interface.cc
@@ -2098,8 +2098,9 @@ void UI_block_draw(const bContext *C, uiBlock *block)
   }
   /* Shared layout panel backdrop style between redo region and popups. */
   if (block->panel && ELEM(region->regiontype, RGN_TYPE_HUD, RGN_TYPE_TEMPORARY)) {
-    /* TODO: Add as theme color. */
-    float subpanel_backcolor[4]{0.2f, 0.3f, 0.33f, 0.05f};
+    float subpanel_backcolor[4];
+    UI_GetThemeColor4fv(TH_POPUP_PANEL_SUB_BACK, subpanel_backcolor);
+
     const bTheme *btheme = UI_GetTheme();
     const float aspect = block->panel->runtime->block->aspect;
     const float radius = btheme->tui.panel_roundness * U.widget_unit * 0.5f / aspect;
diff --git a/source/blender/editors/interface/resources.cc b/source/blender/editors/interface/resources.cc
index 390eff0c935..65d58b97cd3 100644
--- a/source/blender/editors/interface/resources.cc
+++ b/source/blender/editors/interface/resources.cc
@@ -1057,6 +1057,8 @@ const uchar *UI_ThemeGetColorPtr(bTheme *btheme, int spacetype, int colorid)
         case TH_V3D_CLIPPING_BORDER:
           cp = ts->clipping_border_3d;
           break;
+        case TH_POPUP_PANEL_SUB_BACK:
+          cp = btheme->tui.popup_panel_sub_back;
       }
     }
   }
diff --git a/source/blender/makesdna/DNA_userdef_types.h b/source/blender/makesdna/DNA_userdef_types.h
index f40444f8ff9..5639d89cc97 100644
--- a/source/blender/makesdna/DNA_userdef_types.h
+++ b/source/blender/makesdna/DNA_userdef_types.h
@@ -206,7 +206,7 @@ typedef struct ThemeUI {
    * icons. */
   float icon_border_intensity;
   float panel_roundness;
-  char _pad2[4];
+  unsigned char popup_panel_sub_back[4];
 
 } ThemeUI;
 
diff --git a/source/blender/makesrna/intern/rna_userdef.cc b/source/blender/makesrna/intern/rna_userdef.cc
index 7149b31be0f..079bf7bd221 100644
--- a/source/blender/makesrna/intern/rna_userdef.cc
+++ b/source/blender/makesrna/intern/rna_userdef.cc
@@ -1940,6 +1940,14 @@ static void rna_def_userdef_theme_ui(BlenderRNA *brna)
       prop, "Icon Border", "Control the intensity of the border around themes icons");
   RNA_def_property_ui_range(prop, 0.0, 1.0, 0.1, 2);
   RNA_def_property_update(prop, 0, "rna_userdef_theme_update_icons");
+
+  prop = RNA_def_property(srna, "popup_panel_sub_back", PROP_FLOAT, PROP_COLOR_GAMMA);
+  RNA_def_property_float_sdna(prop, nullptr, "popup_panel_sub_back");
+  RNA_def_property_array(prop, 4);
+  RNA_def_property_ui_text(prop,
+                           "Popup layout panel sub background",
+                           "Color of layout panels sub background in popups");
+  RNA_def_property_update(prop, 0, "rna_userdef_theme_update");
 }
 
 static void rna_def_userdef_theme_space_common(StructRNA *srna)