diff --git a/kitty/cell_defines.glsl b/kitty/cell_defines.glsl
index ec6459548..23b1ffd07 100644
--- a/kitty/cell_defines.glsl
+++ b/kitty/cell_defines.glsl
@@ -1,4 +1,3 @@
-#define DO_FG_OVERRIDE {DO_FG_OVERRIDE}
 #define FG_OVERRIDE_THRESHOLD {FG_OVERRIDE_THRESHOLD}
 #define FG_OVERRIDE_ALGO {FG_OVERRIDE_ALGO}
 #define TEXT_NEW_GAMMA {TEXT_NEW_GAMMA}
@@ -25,5 +24,11 @@
 #define ONLY_FOREGROUND
 #endif
 
+#if FG_OVERRIDE_ALGO == 0
+#define DO_FG_OVERRIDE 0
+#else
+#define DO_FG_OVERRIDE 1
+#endif
+
 // Linear space luminance values
 const vec3 Y = vec3(0.2126, 0.7152, 0.0722);
diff --git a/kitty/shaders/legacy.py b/kitty/shaders/legacy.py
index 7fb10c3c9..144b6cad9 100644
--- a/kitty/shaders/legacy.py
+++ b/kitty/shaders/legacy.py
@@ -190,11 +190,13 @@ class LoadShaderPrograms:
             )
 
         def resolve_cell_defines(only_fg: int, only_bg: int, src: str) -> str:
+            algo = '1' if self.text_fg_override_threshold.unit == '%' else '2'
+            if not self.text_fg_override_threshold.scaled_value:
+                algo = '0'
             r = self.cell_program_replacer.replacements
             r['ONLY_FOREGROUND'] = str(only_fg)
             r['ONLY_BACKGROUND'] = str(only_bg)
-            r['DO_FG_OVERRIDE'] = '1' if self.text_fg_override_threshold.scaled_value else '0'
-            r['FG_OVERRIDE_ALGO'] = '1' if self.text_fg_override_threshold.unit == '%' else '2'
+            r['FG_OVERRIDE_ALGO'] = algo
             r['FG_OVERRIDE_THRESHOLD'] = str(self.text_fg_override_threshold.scaled_value)
             r['TEXT_NEW_GAMMA'] = '0' if self.text_old_gamma else '1'
             return self.cell_program_replacer(src)