diff --git a/rtengine/cplx_wavelet_dec.h b/rtengine/cplx_wavelet_dec.h
index 91e71fcd5..c127a7adf 100644
--- a/rtengine/cplx_wavelet_dec.h
+++ b/rtengine/cplx_wavelet_dec.h
@@ -17,9 +17,7 @@
  *  2010 Ilya Popov <ilia_popov@rambler.ru>
  *  2012 Emil Martinec <ejmartin@uchicago.edu>
  */
-
-#ifndef CPLX_WAVELET_DEC_H_INCLUDED
-#define CPLX_WAVELET_DEC_H_INCLUDED
+#pragma once
 
 #include <cstddef>
 #include <cmath>
@@ -266,5 +264,3 @@ void wavelet_decomposition::reconstruct(E * dst, const float blend)
 }
 
 }
-
-#endif
diff --git a/rtengine/cplx_wavelet_filter_coeffs.h b/rtengine/cplx_wavelet_filter_coeffs.h
index 6b8255b89..6287fc03b 100644
--- a/rtengine/cplx_wavelet_filter_coeffs.h
+++ b/rtengine/cplx_wavelet_filter_coeffs.h
@@ -17,7 +17,7 @@
  *  2012 Emil Martinec <ejmartin@uchicago.edu>
  *  2014 Jacques Desmis <jdesmis@gmail.com>
  */
-
+#pragma once
 
 namespace rtengine
 {
diff --git a/rtengine/cplx_wavelet_level.h b/rtengine/cplx_wavelet_level.h
index 4c98addfe..8664606c6 100644
--- a/rtengine/cplx_wavelet_level.h
+++ b/rtengine/cplx_wavelet_level.h
@@ -17,10 +17,8 @@
  *  2010 Ilya Popov <ilia_popov@rambler.ru>
  *  2012 Emil Martinec <ejmartin@uchicago.edu>
  *  2014 Ingo Weyrich <heckflosse@i-weyrich.de>
- */
-
-#ifndef CPLX_WAVELET_LEVEL_H_INCLUDED
-#define CPLX_WAVELET_LEVEL_H_INCLUDED
+*/
+#pragma once
 
 #include <cstddef>
 #include "rt_math.h"
@@ -759,5 +757,3 @@ template<typename T> template<typename E> void wavelet_level<T>::reconstruct_lev
 }
 #endif
 }
-
-#endif
diff --git a/rtengine/improcfun.h b/rtengine/improcfun.h
index 684927e47..9b8d0f63f 100644
--- a/rtengine/improcfun.h
+++ b/rtengine/improcfun.h
@@ -31,13 +31,14 @@
 #include "lcp.h"
 #include "dcp.h"
 #include "curves.h"
-#include "cplx_wavelet_dec.h"
 #include "pipettebuffer.h"
 #include "gamutwarning.h"
 
 namespace rtengine
 {
 
+class wavelet_decomposition;
+
 namespace procparams
 {