diff --git a/source/blender/modifiers/intern/MOD_boolean_util.c b/source/blender/modifiers/intern/MOD_boolean_util.c
index 46d67010d20..c097e9bdf24 100644
--- a/source/blender/modifiers/intern/MOD_boolean_util.c
+++ b/source/blender/modifiers/intern/MOD_boolean_util.c
@@ -434,9 +434,9 @@ static DerivedMesh *ConvertCSGDescriptorsToDerivedMesh(
 		BLI_ghash_free(material_hash, NULL, NULL);
 
 	CDDM_calc_edges(result);
-	CDDM_calc_normals(result);
 
 	dm = CDDM_copy(result, 1); /*builds ngon faces from tess (mface) faces*/
+	CDDM_calc_normals(dm);
 	result->needsFree = 1;
 	result->release(result);
 
diff --git a/source/blender/modifiers/intern/MOD_decimate.c b/source/blender/modifiers/intern/MOD_decimate.c
index 408cc479241..61aae4e573b 100644
--- a/source/blender/modifiers/intern/MOD_decimate.c
+++ b/source/blender/modifiers/intern/MOD_decimate.c
@@ -184,7 +184,7 @@ static DerivedMesh *applyModifier(ModifierData *md, Object *UNUSED(ob),
 	MEM_freeN(lod.triangle_index_buffer);
 
 	dm = CDDM_copy(result, 1); /*builds ngon faces from tess (mface) faces*/
-	CDDM_calc_normals(result);
+	CDDM_calc_normals(dm);
 	result->needsFree = 1;
 	result->release(result);