diff --git a/source/build/include/build.h b/source/build/include/build.h
index e4cfe1503..5b26f736a 100644
--- a/source/build/include/build.h
+++ b/source/build/include/build.h
@@ -1207,12 +1207,6 @@ extern int skiptile;
 
 static vec2_t const zerovec = { 0, 0 };
 
-#ifdef LUNATIC
-extern const int32_t engine_main_arrays_are_static;
-extern const int32_t engine_v8;
-int32_t Mulscale(int32_t a, int32_t b, int32_t sh);
-#endif
-
 static FORCE_INLINE CONSTEXPR int inside_p(int32_t const x, int32_t const y, int const sectnum) { return (sectnum >= 0 && inside(x, y, sectnum) == 1); }
 
 #define SET_AND_RETURN(Lval, Rval) \
diff --git a/source/build/src/engine.cpp b/source/build/src/engine.cpp
index 54bd5c0c4..ad100f1d0 100644
--- a/source/build/src/engine.cpp
+++ b/source/build/src/engine.cpp
@@ -4313,13 +4313,6 @@ int32_t ksqrt(uint32_t num)
     return nsqrtasm(num);
 }
 
-#ifdef LUNATIC
-int32_t Mulscale(int32_t a, int32_t b, int32_t sh)
-{
-    return mulscale(a, b, sh);
-}
-#endif
-
 // Gets the BUILD unit height and z offset of a sprite.
 // Returns the z offset, 'height' may be NULL.
 int32_t spriteheightofsptr(uspriteptr_t spr, int32_t *height, int32_t alsotileyofs)