diff --git a/core/deco.h b/core/deco.h
index ffb52f959..4a10b7366 100644
--- a/core/deco.h
+++ b/core/deco.h
@@ -6,11 +6,29 @@
 extern "C" {
 #endif
 
+struct dive;
+struct deco_state;
+struct decostop;
+
 extern const double buehlmann_N2_t_halflife[];
 
 extern int deco_allowed_depth(double tissues_tolerance, double surface_pressure, const struct dive *dive, bool smooth);
 
 double get_gf(struct deco_state *ds, double ambpressure_bar, const struct dive *dive);
+extern void clear_deco(struct deco_state *ds, double surface_pressure);
+extern void dump_tissues(struct deco_state *ds);
+extern void set_gf(short gflow, short gfhigh);
+extern void set_vpmb_conservatism(short conservatism);
+extern void cache_deco_state(struct deco_state *source, struct deco_state **datap);
+extern void restore_deco_state(struct deco_state *data, struct deco_state *target, bool keep_vpmb_state);
+extern void nuclear_regeneration(struct deco_state *ds, double time);
+extern void vpmb_start_gradient(struct deco_state *ds);
+extern void vpmb_next_gradient(struct deco_state *ds, double deco_time, double surface_pressure);
+extern double tissue_tolerance_calc(struct deco_state *ds, const struct dive *dive, double pressure);
+extern void calc_crushing_pressure(struct deco_state *ds, double pressure);
+extern void vpmb_start_gradient(struct deco_state *ds);
+extern void clear_vpmb_state(struct deco_state *ds);
+extern void printdecotable(struct decostop *table);
 
 extern double regressiona();
 extern double regressionb();
diff --git a/core/dive.h b/core/dive.h
index 406a7b672..40ac9fb00 100644
--- a/core/dive.h
+++ b/core/dive.h
@@ -449,20 +449,9 @@ struct deco_state {
 };
 
 extern void add_segment(struct deco_state *ds, double pressure, struct gasmix gasmix, int period_in_seconds, int setpoint, enum divemode_t divemode, int sac);
-extern void clear_deco(struct deco_state *ds, double surface_pressure);
-extern void dump_tissues(struct deco_state *ds);
-extern void set_gf(short gflow, short gfhigh);
-extern void set_vpmb_conservatism(short conservatism);
-extern void cache_deco_state(struct deco_state *source, struct deco_state **datap);
-extern void restore_deco_state(struct deco_state *data, struct deco_state *target, bool keep_vpmb_state);
-extern void nuclear_regeneration(struct deco_state *ds, double time);
-extern void vpmb_start_gradient(struct deco_state *ds);
-extern void vpmb_next_gradient(struct deco_state *ds, double deco_time, double surface_pressure);
-extern double tissue_tolerance_calc(struct deco_state *ds, const struct dive *dive, double pressure);
 extern bool is_dc_planner(const struct divecomputer *dc);
 extern bool has_planned(const struct dive *dive, bool planned);
 
-
 /* this should be converted to use our types */
 struct divedatapoint {
 	int time;
@@ -499,10 +488,6 @@ struct decostop {
 	int time;
 };
 extern bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, int timestep, struct decostop *decostoptable, struct deco_state **cached_datap, bool is_planner, bool show_disclaimer);
-extern void calc_crushing_pressure(struct deco_state *ds, double pressure);
-extern void vpmb_start_gradient(struct deco_state *ds);
-extern void clear_vpmb_state(struct deco_state *ds);
-extern void printdecotable(struct decostop *table);
 
 /* Since C doesn't have parameter-based overloading, two versions of get_next_event. */
 extern const struct event *get_next_event(const struct event *event, const char *name);
diff --git a/core/divelist.c b/core/divelist.c
index 292e90c73..71a4b9bda 100644
--- a/core/divelist.c
+++ b/core/divelist.c
@@ -12,6 +12,7 @@
 #include <libxslt/transform.h>
 
 #include "subsurface-string.h"
+#include "deco.h"
 #include "divesite.h"
 #include "divelist.h"
 #include "display.h"
diff --git a/core/settings/qPrefTechnicalDetails.cpp b/core/settings/qPrefTechnicalDetails.cpp
index 78e2c13d0..22cea8c74 100644
--- a/core/settings/qPrefTechnicalDetails.cpp
+++ b/core/settings/qPrefTechnicalDetails.cpp
@@ -1,8 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include "qPrefTechnicalDetails.h"
 #include "qPrefPrivate.h"
-
-
+#include "core/deco.h"
 
 static const QString group = QStringLiteral("TecDetails");
 
diff --git a/desktop-widgets/preferences/preferences_graph.cpp b/desktop-widgets/preferences/preferences_graph.cpp
index 2b3c35135..74c248dc4 100644
--- a/desktop-widgets/preferences/preferences_graph.cpp
+++ b/desktop-widgets/preferences/preferences_graph.cpp
@@ -7,7 +7,7 @@
 #include <QMessageBox>
 
 #include "qt-models/models.h"
-#include "core/dive.h" // TODO: replace by deco.h
+#include "core/deco.h"
 
 PreferencesGraph::PreferencesGraph() : AbstractPreferencesWidget(tr("Profile"), QIcon(":graph-icon"), 5)
 {
diff --git a/desktop-widgets/preferences/preferences_graph.h b/desktop-widgets/preferences/preferences_graph.h
index 4fc9cd5b3..8b0ea1adc 100644
--- a/desktop-widgets/preferences/preferences_graph.h
+++ b/desktop-widgets/preferences/preferences_graph.h
@@ -23,7 +23,6 @@ private slots:
 
 private:
 	Ui::PreferencesGraph *ui;
-
 };
 
 #endif
diff --git a/qt-models/diveplannermodel.cpp b/qt-models/diveplannermodel.cpp
index 2dfeff7eb..5a8889802 100644
--- a/qt-models/diveplannermodel.cpp
+++ b/qt-models/diveplannermodel.cpp
@@ -9,6 +9,7 @@
 #include "core/settings/qPrefDivePlanner.h"
 #include "desktop-widgets/command.h"
 #include "core/gettextfromc.h"
+#include "core/deco.h"
 #include <QApplication>
 #include <QTextDocument>
 #include <QtConcurrent>