diff --git a/src/colours.cc b/src/colours.cc
index 9392ea336..0de586e18 100644
--- a/src/colours.cc
+++ b/src/colours.cc
@@ -29,16 +29,17 @@
 
 #include "colours.h"
 
-#include "conky.h"
-#include "gui.h"
 #include "logging.h"
 
+#include <optional>
+
 #ifdef BUILD_X11
+#include <X11/Xlib.h>
 #include <string.h>
 #include <strings.h>
-
-#include <X11/Xlib.h>
 #endif /* BUILD_X11 */
+
+// sourced from X11, doesn't actually need X11
 #include "x11-color.h"
 
 Colour Colour::from_argb32(uint32_t argb) {
diff --git a/src/colours.h b/src/colours.h
index 12861bf1b..a6d526816 100644
--- a/src/colours.h
+++ b/src/colours.h
@@ -26,15 +26,18 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
-#pragma once
 
-#include <config.h>
+#ifndef _COLOURS_H_
+#define _COLOURS_H_
+
+#include "config.h"
+
 #include <cassert>
 #include <climits>
 #include <memory>
-#include <optional>
 #include <string>
 #include <unordered_map>
+
 #ifdef BUILD_X11
 #include <X11/Xlib.h>
 #endif /* BUILD_X11 */
@@ -92,3 +95,5 @@ struct Colour {
 const Colour ERROR_COLOUR = Colour{UINT8_MAX, 0, 0, UINT8_MAX};
 
 Colour parse_color(const std::string &color);
+
+#endif /* _COLOURS_H_ */
diff --git a/src/conky-imlib2.cc b/src/conky-imlib2.cc
index c898498b7..f07ebe751 100644
--- a/src/conky-imlib2.cc
+++ b/src/conky-imlib2.cc
@@ -22,8 +22,9 @@
  */
 
 #include "conky-imlib2.h"
-#include "config.h"
-#include "conky.h"
+
+#include "common.h"
+#include "display-output.hh"
 #include "logging.h"
 #include "text_object.h"
 
@@ -292,3 +293,5 @@ void cimlib_render(int x, int y, int width, int height) {
 void print_image_callback(struct text_object *obj, char *, unsigned int) {
   cimlib_add_image(obj->data.s);
 }
+
+imlib_cache_size_setting imlib_cache_size;
diff --git a/src/conky-imlib2.h b/src/conky-imlib2.h
index 4484dc855..18336f6c1 100644
--- a/src/conky-imlib2.h
+++ b/src/conky-imlib2.h
@@ -24,7 +24,8 @@
 #ifndef _CONKY_IMBLI2_H_
 #define _CONKY_IMBLI2_H_
 
-#include "conky.h"
+#include "setting.hh"
+#include "text_object.h"
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wvariadic-macros"
diff --git a/src/conky.cc b/src/conky.cc
index 99222d7f3..2ebeff94a 100644
--- a/src/conky.cc
+++ b/src/conky.cc
@@ -29,6 +29,8 @@
 
 #include "conky.h"
 
+#include "config.h"
+
 #include <algorithm>
 #include <cerrno>
 #include <climits>
@@ -63,7 +65,6 @@
 #endif /* HAVE_DIRENT_H */
 
 #include "common.h"
-#include "config.h"
 #include "text_object.h"
 
 #ifdef BUILD_WAYLAND
@@ -407,18 +408,6 @@ int calc_text_width(const char *s) {
   return slen;
 }
 
-int dpi_scale(int value) {
-#ifdef BUILD_GUI
-  if (display_output()) {
-    return display_output()->dpi_scale(value);
-  } else {
-    return value;
-  }
-#else  /* BUILD_GUI */
-  return value;
-#endif /* BUILD_GUI */
-}
-
 #ifdef BUILD_GUI
 conky::gradient_factory *create_gradient_factory(int width, Colour first_colour,
                                                  Colour last_colour) {
diff --git a/src/conky.h b/src/conky.h
index 1592a50b4..bd2059a8f 100644
--- a/src/conky.h
+++ b/src/conky.h
@@ -32,11 +32,14 @@
 
 #define __STDC_FORMAT_MACROS
 
+#include "config.h"
+
 #include <arpa/inet.h>
 #include <config.h>      /* defines */
 #include <sys/utsname.h> /* struct uname_s */
 #include <csignal>
 #include <memory>
+
 #include "colours.h"
 #include "common.h" /* at least for struct dns_data */
 #include "luamm.hh"
@@ -311,8 +314,6 @@ void set_updatereset(int);
 int get_updatereset(void);
 int get_total_updates(void);
 
-int dpi_scale(int value);
-
 int get_saved_coordinates_x(int);
 int get_saved_coordinates_y(int);
 
diff --git a/src/core.cc b/src/core.cc
index 6145a17fb..0ce2cbdcb 100644
--- a/src/core.cc
+++ b/src/core.cc
@@ -27,9 +27,12 @@
  *
  */
 
+#include "config.h"
+
 /* local headers */
-#include "core.h"
 #include "algebra.h"
+#include "core.h"
+
 #include "bsdapm.h"
 #include "build.h"
 #include "colour-settings.h"
@@ -40,11 +43,11 @@
 #include "exec.h"
 #include "i8k.h"
 #include "misc.h"
+#include "proc.h"
 #include "text_object.h"
 #ifdef BUILD_IMLIB2
 #include "conky-imlib2.h"
 #endif /* BUILD_IMLIB2 */
-#include "proc.h"
 #ifdef BUILD_MYSQL
 #include "mysql.h"
 #endif /* BUILD_MYSQL */
@@ -1893,9 +1896,10 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   obj->callbacks.print = &print_combine;
   obj->callbacks.free = &free_combine;
 #ifdef BUILD_NVIDIA
-  END OBJ_ARG(
-      nvidia, 0,
-      "nvidia needs an argument") if (set_nvidia_query(obj, arg, text_node_t::NONSPECIAL)) {
+  END OBJ_ARG(nvidia, 0, "nvidia needs an argument") if (set_nvidia_query(
+                                                             obj, arg,
+                                                             text_node_t::
+                                                                 NONSPECIAL)) {
     CRIT_ERR_FREE(obj, free_at_crash,
                   "nvidia: invalid argument"
                   " specified: '%s'",
@@ -1905,7 +1909,8 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   obj->callbacks.free = &free_nvidia;
   END OBJ_ARG(
       nvidiabar, 0,
-      "nvidiabar needs an argument") if (set_nvidia_query(obj, arg, text_node_t::BAR)) {
+      "nvidiabar needs an argument") if (set_nvidia_query(obj, arg,
+                                                          text_node_t::BAR)) {
     CRIT_ERR_FREE(obj, free_at_crash,
                   "nvidiabar: invalid argument"
                   " specified: '%s'",
@@ -1915,7 +1920,9 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   obj->callbacks.free = &free_nvidia;
   END OBJ_ARG(
       nvidiagraph, 0,
-      "nvidiagraph needs an argument") if (set_nvidia_query(obj, arg, text_node_t::GRAPH)) {
+      "nvidiagraph needs an argument") if (set_nvidia_query(obj, arg,
+                                                            text_node_t::
+                                                                GRAPH)) {
     CRIT_ERR_FREE(obj, free_at_crash,
                   "nvidiagraph: invalid argument"
                   " specified: '%s'",
@@ -1925,7 +1932,9 @@ struct text_object *construct_text_object(char *s, const char *arg, long line,
   obj->callbacks.free = &free_nvidia;
   END OBJ_ARG(
       nvidiagauge, 0,
-      "nvidiagauge needs an argument") if (set_nvidia_query(obj, arg, text_node_t::GAUGE)) {
+      "nvidiagauge needs an argument") if (set_nvidia_query(obj, arg,
+                                                            text_node_t::
+                                                                GAUGE)) {
     CRIT_ERR_FREE(obj, free_at_crash,
                   "nvidiagauge: invalid argument"
                   " specified: '%s'",
diff --git a/src/display-http.hh b/src/display-http.hh
index 550b25fb1..300028600 100644
--- a/src/display-http.hh
+++ b/src/display-http.hh
@@ -25,10 +25,6 @@
 
 #include "config.h"
 
-#ifndef BUILD_HTTP
-#error display-http.hh included when BUILD_HTTP is disabled
-#endif
-
 #include <limits>
 #include <string>
 #include <type_traits>
diff --git a/src/display-ncurses.hh b/src/display-ncurses.hh
index 6c2e4ff09..2d1c1a0b8 100644
--- a/src/display-ncurses.hh
+++ b/src/display-ncurses.hh
@@ -25,10 +25,6 @@
 
 #include "config.h"
 
-#ifndef BUILD_NCURSES
-#error display-ncurses.hh included when BUILD_NCURSES is disabled
-#endif
-
 #include <limits>
 #include <string>
 #include <type_traits>
diff --git a/src/display-output.hh b/src/display-output.hh
index 27f95bbb0..e74733ef9 100644
--- a/src/display-output.hh
+++ b/src/display-output.hh
@@ -107,7 +107,11 @@ class display_output_base {
   virtual void draw_arc(int /*x*/, int /*y*/, int /*w*/, int /*h*/, int /*a1*/,
                         int /*a2*/) {}
   virtual void move_win(int /*x*/, int /*y*/) {}
-  virtual int dpi_scale(int value) { return value; }
+  template <typename T, typename = typename std::enable_if<
+                            std::is_arithmetic<T>::value, T>::type>
+  T dpi_scale(T value) {
+    return value;
+  }
 
   virtual void begin_draw_stuff() {}
   virtual void end_draw_stuff() {}
@@ -182,6 +186,21 @@ static inline conky::display_output_base *display_output() {
   return nullptr;
 }
 
+template <typename T, typename = typename std::enable_if<
+                          std::is_arithmetic<T>::value, T>::type>
+inline T dpi_scale(T value) {
+#ifdef BUILD_GUI
+  auto output = display_output();
+  if (output) {
+    return output->dpi_scale(value);
+  } else {
+    return value;
+  }
+#else  /* BUILD_GUI */
+  return value;
+#endif /* BUILD_GUI */
+}
+
 static inline void unset_display_output() {
   conky::current_display_outputs.clear();
 }
diff --git a/src/display-wayland.cc b/src/display-wayland.cc
index c8fd8c5df..9505eb4da 100644
--- a/src/display-wayland.cc
+++ b/src/display-wayland.cc
@@ -913,8 +913,10 @@ void display_output_wayland::move_win(int x, int y) {
   // window.y = y;
   // TODO
 }
-
-int display_output_wayland::dpi_scale(int value) { return value; }
+template <typename T, typename>
+T display_output_wayland::dpi_scale(T value) {
+  return value;
+}
 
 void display_output_wayland::end_draw_stuff() {
   window_commit_buffer(global_window);
diff --git a/src/display-wayland.hh b/src/display-wayland.hh
index e6d26896f..6bc60da5f 100644
--- a/src/display-wayland.hh
+++ b/src/display-wayland.hh
@@ -25,10 +25,6 @@
 
 #include "config.h"
 
-#ifndef BUILD_WAYLAND
-#error display-wayland.hh included when BUILD_WAYLAND is disabled
-#endif
-
 #include <limits>
 #include <string>
 #include <type_traits>
@@ -75,7 +71,9 @@ class display_output_wayland : public display_output_base {
   virtual void fill_rect(int, int, int, int);
   virtual void draw_arc(int, int, int, int, int, int);
   virtual void move_win(int, int);
-  virtual int dpi_scale(int);
+  template <typename T, typename = typename std::enable_if<
+                            std::is_arithmetic<T>::value, T>::type>
+  T dpi_scale(T value);
 
   virtual void end_draw_stuff();
   virtual void clear_text(int);
diff --git a/src/display-x11.cc b/src/display-x11.cc
index 4bce1d3dc..f9b179149 100644
--- a/src/display-x11.cc
+++ b/src/display-x11.cc
@@ -974,10 +974,12 @@ void display_output_x11::move_win(int x, int y) {
 #endif /* OWN_WINDOW */
 }
 
-int display_output_x11::dpi_scale(int value) {
+const size_t PIXELS_PER_INCH = 96;
+template <typename T, typename>
+T display_output_x11::dpi_scale(T value) {
 #if defined(BUILD_XFT)
   if (use_xft.get(*state) && xft_dpi > 0) {
-    return (value * xft_dpi + (value > 0 ? 48 : -48)) / 96;
+    return (value * xft_dpi + (value > 0 ? 48 : -48)) / PIXELS_PER_INCH;
   } else {
     return value;
   }
diff --git a/src/display-x11.hh b/src/display-x11.hh
index c34795d66..131a886e0 100644
--- a/src/display-x11.hh
+++ b/src/display-x11.hh
@@ -25,10 +25,6 @@
 
 #include "config.h"
 
-#ifndef BUILD_X11
-#error display-x11.hh included when BUILD_X11 is disabled
-#endif
-
 #include <limits>
 #include <string>
 #include <type_traits>
@@ -73,7 +69,9 @@ class display_output_x11 : public display_output_base {
   virtual void fill_rect(int, int, int, int);
   virtual void draw_arc(int, int, int, int, int, int);
   virtual void move_win(int, int);
-  virtual int dpi_scale(int);
+  template <typename T, typename = typename std::enable_if<
+                            std::is_arithmetic<T>::value, T>::type>
+  T dpi_scale(T value);
 
   virtual void end_draw_stuff();
   virtual void clear_text(int);
diff --git a/src/gui.cc b/src/gui.cc
index 9bd931ed5..5e6d242e2 100644
--- a/src/gui.cc
+++ b/src/gui.cc
@@ -37,9 +37,9 @@
 #include "wl.h"
 #endif /* BUILD_WAYLAND */
 
-#ifdef BUILD_IMLIB2
-#include "conky-imlib2.h"
-#endif /* BUILD_IMLIB2 */
+// #ifdef BUILD_IMLIB2
+// #include "conky-imlib2.h"
+// #endif /* BUILD_IMLIB2 */
 #ifndef OWN_WINDOW
 #include <iostream>
 #endif
diff --git a/src/text_object.h b/src/text_object.h
index c21bb13b7..b6f3c6d5b 100644
--- a/src/text_object.h
+++ b/src/text_object.h
@@ -29,11 +29,13 @@
 #ifndef _TEXT_OBJECT_H
 #define _TEXT_OBJECT_H
 
-#include <stdint.h> /* uint8_t */
-#include "config.h" /* for the defines */
+#include "config.h"
+
 #include "exec.h"
 #include "specials.h" /* enum special_types */
 
+#include <cstdint> /* uint8_t */
+
 enum class draw_mode_t : uint32_t {
   BG = static_cast<uint32_t>(text_node_t::BG),
   FG = static_cast<uint32_t>(text_node_t::FG),
diff --git a/src/x11-settings.cc b/src/x11-settings.cc
index 09abcb51e..d8b4effa6 100644
--- a/src/x11-settings.cc
+++ b/src/x11-settings.cc
@@ -124,11 +124,3 @@ priv::use_xdbe_setting use_xdbe;
 #else
 priv::use_xpmdb_setting use_xpmdb;
 #endif
-
-#ifdef BUILD_IMLIB2
-/*
- * the only reason this is not in imlib2.cc is so that we can be sure it's
- * setter executes after use_xdbe
- */
-imlib_cache_size_setting imlib_cache_size;
-#endif