diff --git a/code/hud/hudbrackets.cpp b/code/hud/hudbrackets.cpp
index f8fed8d28d..65448e64ea 100644
--- a/code/hud/hudbrackets.cpp
+++ b/code/hud/hudbrackets.cpp
@@ -645,7 +645,7 @@ void HudGaugeBrackets::render(float frametime)
 void HudGaugeBrackets::renderObjectBrackets(object *targetp, color *clr, int w_correction, int h_correction, int flags)
 {
 	int x1,x2,y1,y2;
-	int draw_box = true;
+	bool draw_box = true;
 	int bound_rc;
 	SCP_list<CJumpNode>::iterator jnp;
 
diff --git a/code/missionui/missionscreencommon.cpp b/code/missionui/missionscreencommon.cpp
index 11cc0f9c49..9c0c022849 100644
--- a/code/missionui/missionscreencommon.cpp
+++ b/code/missionui/missionscreencommon.cpp
@@ -1601,7 +1601,7 @@ void draw_model_rotating(int model_id, int x1, int y1, int x2, int y2, float *ro
 		}
 		g3_done_instance(true);
 
-		gr_zbuffer_set(false); // Turn of Depthbuffer so we dont get gridlines over the ship or a disappearing scanline 
+		gr_zbuffer_set(GR_ZBUFF_NONE); // Turn of Depthbuffer so we dont get gridlines over the ship or a disappearing scanline 
 		if (time >= 0.5f) { // Phase 1 onward draw the grid
 			int i;
 			start.xyz.y = -offset;
@@ -1669,7 +1669,7 @@ void draw_model_rotating(int model_id, int x1, int y1, int x2, int y2, float *ro
 			}
 		}
 
-		gr_zbuffer_set(true); // Turn of depthbuffer again
+		gr_zbuffer_set(GR_ZBUFF_FULL); // Turn of depthbuffer again
 		gr_end_view_matrix();
 		gr_end_proj_matrix();
 		g3_end_frame();
diff --git a/code/object/collideshipweapon.cpp b/code/object/collideshipweapon.cpp
index 7fb20c81ad..c75e946774 100644
--- a/code/object/collideshipweapon.cpp
+++ b/code/object/collideshipweapon.cpp
@@ -263,7 +263,7 @@ int ship_weapon_check_collision(object *ship_objp, object *weapon_objp, float ti
 
         if (vm_vec_dot(&hit_direction, &warp_orient.vec.fvec) < 0.0f)
         {
-             valid_hit_occurred = false;
+             valid_hit_occurred = 0;
         }
     }
 
diff --git a/code/parse/lua.cpp b/code/parse/lua.cpp
index b2d326d68b..9ae74657ca 100644
--- a/code/parse/lua.cpp
+++ b/code/parse/lua.cpp
@@ -10347,11 +10347,11 @@ ADE_VIRTVAR(MouseControlStatus, l_Mouse, "boolean", "Gets and sets the retail mo
 	{
 		if (newVal)
 		{
-			Use_mouse_to_fly = true;
+			Use_mouse_to_fly = 1;
 		}
 		else
 		{
-			Use_mouse_to_fly = false;
+			Use_mouse_to_fly = 0;
 		}
 	}
 
diff --git a/code/parse/sexp.cpp b/code/parse/sexp.cpp
index eeb831c606..0c09eb64e0 100644
--- a/code/parse/sexp.cpp
+++ b/code/parse/sexp.cpp
@@ -17412,7 +17412,7 @@ int is_nav_linked(int node)
 			return (Ships[i].flags2 & SF2_NAVPOINT_CARRY) != 0;
 		}
 	}
-	return false;
+	return 0;
 }
 
 //text: distance-to-nav
diff --git a/code/radar/radardradis.cpp b/code/radar/radardradis.cpp
index c34d087ac5..49c88055f6 100644
--- a/code/radar/radardradis.cpp
+++ b/code/radar/radardradis.cpp
@@ -301,7 +301,7 @@ void HudGaugeRadarDradis::setupViewHtl()
 	gr_set_proj_matrix(.625f * PI_2, i2fl(Radar_radius[0])/i2fl(Radar_radius[1]), 0.001f, 5.0f);
 	gr_set_view_matrix(&Orb_eye_position, &vmd_identity_matrix);
 
-	gr_zbuffer_set(0);
+	gr_zbuffer_set(GR_ZBUFF_NONE);
 }
 
 void HudGaugeRadarDradis::doneDrawingHtl()
@@ -311,7 +311,7 @@ void HudGaugeRadarDradis::doneDrawingHtl()
 	
 	//hud_save_restore_camera_data(0);
 
-	gr_zbuffer_set(1);
+	gr_zbuffer_set(GR_ZBUFF_FULL);
 }
 
 void HudGaugeRadarDradis::drawOutlinesHtl()
diff --git a/code/radar/radarorb.cpp b/code/radar/radarorb.cpp
index 63ba1a5aea..73485949b1 100644
--- a/code/radar/radarorb.cpp
+++ b/code/radar/radarorb.cpp
@@ -352,7 +352,7 @@ void HudGaugeRadarOrb::doneDrawingHtl()
 	gr_end_view_matrix();
 	gr_end_proj_matrix();
 	resetClip();
-    gr_zbuffer_set(1);
+    gr_zbuffer_set(GR_ZBUFF_FULL);
 }
 
 void HudGaugeRadarOrb::drawOutlines()
@@ -681,5 +681,5 @@ void HudGaugeRadarOrb::setupViewHtl()
     gr_set_proj_matrix( .625f * PI_2, float(w)/float(h), 0.001f, 5.0f);
 	gr_set_view_matrix( &Orb_eye_position, &vmd_identity_matrix );
 
-    gr_zbuffer_set(0);
+    gr_zbuffer_set(GR_ZBUFF_NONE);
 }
\ No newline at end of file