diff --git a/SConstruct b/SConstruct
index 56075eea6..b1c940a03 100644
--- a/SConstruct
+++ b/SConstruct
@@ -762,7 +762,7 @@ class DXXProgram(DXXCommon):
 'main/effects.cpp',
 'main/fvi.cpp',
 'main/game.cpp',
-'main/gamecntl.c',
+'main/gamecntl.cpp',
 'main/gamefont.c',
 'main/gamerend.c',
 'main/gamesave.c',
diff --git a/common/main/aistruct.h b/common/main/aistruct.h
index 9e866722f..5ca376837 100644
--- a/common/main/aistruct.h
+++ b/common/main/aistruct.h
@@ -26,6 +26,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "inferno.h"
 #include "polyobj.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define GREEN_GUY   1
 
 #define MAX_SEGMENTS_PER_PATH       20
@@ -311,4 +315,8 @@ typedef struct {
 
 extern void ai_do_cloak_stuff(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _AISTRUCT_H */
diff --git a/common/main/escort.h b/common/main/escort.h
index 3cdcc48b3..3f3540617 100644
--- a/common/main/escort.h
+++ b/common/main/escort.h
@@ -6,6 +6,11 @@
 
 #ifndef _ESCORT_H
 #define _ESCORT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #if defined(DXX_BUILD_DESCENT_I)
 static inline void invalidate_escort_goal(void)
 {
@@ -27,4 +32,9 @@ void invalidate_escort_goal(void);
 void drop_stolen_items (struct object *);
 extern fix64	Buddy_sorry_time;
 #endif
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif // _ESCORT_H
diff --git a/common/main/lighting.h b/common/main/lighting.h
index 83d19329e..ab0879d47 100644
--- a/common/main/lighting.h
+++ b/common/main/lighting.h
@@ -21,6 +21,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #ifndef _LIGHTING_H
 #define _LIGHTING_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define MAX_LIGHT       0x10000     // max value
 
 #define MIN_LIGHT_DIST  (F1_0*4)
@@ -50,4 +54,8 @@ g3s_lrgb compute_object_light(object *obj,vms_vector *rotated_pnt);
 void toggle_headlight_active(void);
 void start_lighting_frame(struct object *viewer);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _LIGHTING_H */
diff --git a/common/main/playsave.h b/common/main/playsave.h
index 968c148cd..770b47997 100644
--- a/common/main/playsave.h
+++ b/common/main/playsave.h
@@ -31,6 +31,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "escort.h"
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define N_SAVE_SLOTS    10
 #define GAME_NAME_LEN   25      // +1 for terminating zero = 26
 
@@ -136,4 +140,8 @@ struct netgame_info;
 void read_netgame_profile(struct netgame_info *ng);
 void write_netgame_profile(struct netgame_info *ng);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _PLAYSAVE_H */
diff --git a/common/main/powerup.h b/common/main/powerup.h
index ee3fd0872..43ec768cf 100644
--- a/common/main/powerup.h
+++ b/common/main/powerup.h
@@ -24,6 +24,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "dxxsconf.h"
 #include "vclip.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 enum powerup_type_t
 {
 	POW_EXTRA_LIFE = 0,
@@ -141,4 +145,8 @@ extern void powerup_basic(int redadd, int greenadd, int blueadd, int score, cons
  */
 extern int powerup_type_info_read_n(powerup_type_info *pti, int n, PHYSFS_file *fp);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _POWERUP_H */
diff --git a/common/main/slew.h b/common/main/slew.h
index 2e2004617..a7d69b1ad 100644
--- a/common/main/slew.h
+++ b/common/main/slew.h
@@ -23,6 +23,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 
 #include "object.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 //from slew.c
 
 #if 1   //ndef RELEASE  //kill error on RELEASE build
@@ -41,4 +45,8 @@ int slew_frame(int dont_check_keys);        // Does slew frame
 
 #endif
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _SLEW_H */
diff --git a/common/main/state.h b/common/main/state.h
index 7c3524c96..40209ea6e 100644
--- a/common/main/state.h
+++ b/common/main/state.h
@@ -32,6 +32,10 @@ extern int state_save_old_game(int slotnum, const char * sg_name, player_rw * sg
 #define SECRETC_FILENAME	GameArg.SysUsePlayersDir? "Players/secret.sgc" : "secret.sgc"
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int state_save_all(int secret_save, const char *filename_override, int blind_save);
 int state_restore_all(int in_game, int secret_restore, const char *filename_override);
 
@@ -52,4 +56,8 @@ static inline void set_pos_from_return_segment(void)
 void set_pos_from_return_segment(void);
 #endif
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _STATE_H */
diff --git a/common/main/titles.h b/common/main/titles.h
index 625a62d14..a2e4ddbc8 100644
--- a/common/main/titles.h
+++ b/common/main/titles.h
@@ -20,6 +20,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #ifndef _TITLES_H
 #define _TITLES_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 extern void show_titles(void);
 extern void do_briefing_screens(const char *filename, int level_num);
 extern void do_end_briefing_screens(const char *filename);
@@ -31,4 +35,8 @@ extern int intro_played;
 #endif
 extern void show_order_form(void);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif
diff --git a/d2x-rebirth/main/movie.h b/d2x-rebirth/main/movie.h
index becff3bac..880a0acb7 100644
--- a/d2x-rebirth/main/movie.h
+++ b/d2x-rebirth/main/movie.h
@@ -20,6 +20,10 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #ifndef _MOVIE_H
 #define _MOVIE_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define MOVIE_ABORT_ON  1
 #define MOVIE_ABORT_OFF 0
 
@@ -50,4 +54,8 @@ void init_extra_robot_movie(char *filename);
 
 extern int MovieHires;      // specifies whether movies use low or high res
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* _MOVIE_H */
diff --git a/similar/main/gamecntl.c b/similar/main/gamecntl.cpp
similarity index 99%
rename from similar/main/gamecntl.c
rename to similar/main/gamecntl.cpp
index d3bbeee3b..37adceb4e 100644
--- a/similar/main/gamecntl.c
+++ b/similar/main/gamecntl.cpp
@@ -19,6 +19,9 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 
 //#define DOOR_DEBUGGING
 
+#define __STDC_FORMAT_MACROS	// For PRIi64
+
+#include <algorithm>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -100,6 +103,8 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 
 #include <SDL.h>
 
+using std::min;
+
 // Global Variables -----------------------------------------------------------
 
 int	Debug_spew;