diff --git a/src/config.c b/src/config.c
index 647f59e4f7..cd6057d65b 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1493,7 +1493,7 @@ static void title_sequence_open(const char *path, const char *customName)
 		token = &parts[0 * 128];
 		part1 = &parts[1 * 128];
 		part2 = &parts[2 * 128];
-		title_command command;
+		title_command command = { 0 };
 		command.command = 0xFF;
 
 		if (token[0] != 0) {
diff --git a/src/peep/staff.c b/src/peep/staff.c
index 3d44d0cb53..b187d632b3 100644
--- a/src/peep/staff.c
+++ b/src/peep/staff.c
@@ -389,6 +389,7 @@ uint16 hire_new_staff_member(uint8 staffType)
 	RCT2_GLOBAL(RCT2_ADDRESS_GAME_COMMAND_ERROR_TITLE, uint16) = STR_CANT_HIRE_NEW_STAFF;
 
 	int eax, ebx, ecx, edx, esi, edi, ebp;
+	ecx = edx = esi = edi = ebp = 0;
 	eax = 0x8000;
 	ebx = staffType << 8 | GAME_COMMAND_FLAG_APPLY;
 
diff --git a/src/ride/ride.c b/src/ride/ride.c
index bb7261ad5b..573251d0d1 100644
--- a/src/ride/ride.c
+++ b/src/ride/ride.c
@@ -850,6 +850,7 @@ int ride_create_ride(ride_list_item listItem)
 	ebx = GAME_COMMAND_FLAG_APPLY;
 	edi = 0;
 	esi = 0;
+	ebp = 0;
 
 	RCT2_GLOBAL(RCT2_ADDRESS_GAME_COMMAND_ERROR_TITLE, uint16) = 0x3DC;
 
@@ -1194,7 +1195,7 @@ int sub_6C683D(int* x, int* y, int* z, int direction, int type, uint16 extra_par
 			mapElement->properties.track.colour &= 0x0F;
 			mapElement->properties.track.colour |= (extra_params & 0xFF) << 4;
 		}
-		
+
 		if (flags & (1 << 3)) {
 			track_element_set_cable_lift(mapElement);
 		}
@@ -5562,7 +5563,7 @@ void game_command_callback_ride_remove_track_piece(int eax, int ebx, int ecx, in
 	z = gRideRemoveTrackPieceCallbackZ;
 	direction = gRideRemoveTrackPieceCallbackDirection;
 	type = gRideRemoveTrackPieceCallbackType;
-	
+
 	window_ride_construction_mouseup_demolish_next_piece(x, y, z, direction, type);
 }
 
@@ -6412,9 +6413,9 @@ static void ride_update_vehicle_colours(int rideIndex)
 {
 	rct_ride *ride;
 	rct_vehicle *vehicle;
-	rct_vehicle_colour colours;
+	rct_vehicle_colour colours = { 0 };
 	uint16 spriteIndex;
-	uint8 coloursExtended;
+	uint8 coloursExtended = 0;
 
 	ride = GET_RIDE(rideIndex);
 	if (ride->type == RIDE_TYPE_SPACE_RINGS || ride_type_has_flag(ride->type, RIDE_TYPE_FLAG_16)) {
diff --git a/src/scenario.c b/src/scenario.c
index 4d94b7be70..6975421c80 100644
--- a/src/scenario.c
+++ b/src/scenario.c
@@ -497,7 +497,7 @@ void scenario_success_submit_name(const char *name)
  **/
 void scenario_entrance_fee_too_high_check()
 {
-	uint16 x, y;
+	uint16 x = 0, y = 0;
 	uint16 totalRideValue = RCT2_GLOBAL(RCT2_TOTAL_RIDE_VALUE, uint16);
 	uint16 park_entrance_fee = RCT2_GLOBAL(RCT2_ADDRESS_PARK_ENTRANCE_FEE, uint16);
 	int max_fee = totalRideValue + (totalRideValue / 2);
diff --git a/src/windows/map.c b/src/windows/map.c
index 163604d879..7c46d62645 100644
--- a/src/windows/map.c
+++ b/src/windows/map.c
@@ -1597,7 +1597,7 @@ static uint16 map_window_get_pixel_colour_ride(int x, int y)
 
 static void map_window_set_pixels(rct_window *w)
 {
-	uint16 colour, *destination;
+	uint16 colour = 0, *destination;
 	int x, y, dx, dy;
 
 	destination = (uint16*)((RCT2_GLOBAL(0x00F1AD6C, uint32) * 511) + RCT2_GLOBAL(RCT2_ADDRESS_MAP_IMAGE_DATA, uint32) + 255);
diff --git a/src/windows/park.c b/src/windows/park.c
index 6b32b71bed..91be02ae90 100644
--- a/src/windows/park.c
+++ b/src/windows/park.c
@@ -1053,6 +1053,7 @@ static void window_park_entrance_paint(rct_window *w, rct_drawpixelinfo *dpi)
 static void window_park_init_viewport(rct_window *w)
 {
 	int i, x, y, z, r, xy, zr, viewportFlags;
+	x = y = z = r = xy = zr = 0;
 	rct_viewport *viewport;
 	rct_widget *viewportWidget;
 
diff --git a/src/windows/ride.c b/src/windows/ride.c
index b04e0f2cb7..b6f44dde0b 100644
--- a/src/windows/ride.c
+++ b/src/windows/ride.c
@@ -5341,6 +5341,9 @@ static void window_ride_graphs_scrollpaint(rct_window *w, rct_drawpixelinfo *dpi
 			top = measurement->lateral[x] + 52;
 			bottom = measurement->lateral[x + 1] + 52;
 			break;
+		default:
+			log_error("Wrong graph type %d", listType);
+			top = bottom = 0;
 		}
 
 		top = widget->bottom - widget->top - top - 13;
diff --git a/src/windows/ride_construction.c b/src/windows/ride_construction.c
index 02de05c631..b3dae4b8de 100644
--- a/src/windows/ride_construction.c
+++ b/src/windows/ride_construction.c
@@ -2273,7 +2273,7 @@ static void sub_6CBCE2(
 			offsetX = -trackBlock->y;
 			offsetY =  trackBlock->x;
 			bl = rol8(bl, 3);
-			bh |= bl;
+			bh = bl;
 			bh = ror8(bh, 4);
 			bl &= 0x88;
 			bh &= 0x77;
diff --git a/src/windows/title_editor.c b/src/windows/title_editor.c
index eb82afe2a8..41c2974acd 100644
--- a/src/windows/title_editor.c
+++ b/src/windows/title_editor.c
@@ -943,7 +943,7 @@ void window_title_editor_scrollpaint(rct_window *w, rct_drawpixelinfo *dpi, int
 				gfx_fill_rect(dpi, x, y, x + SCROLL_WIDTH + 100, y + ROW_HEIGHT - 1, ColourMapA[w->colours[1]].lighter | 0x1000000);
 			}
 
-			rct_string_id commandName;
+			rct_string_id commandName = STR_NONE;
 			switch (command->command) {
 			case TITLE_SCRIPT_LOAD:
 				commandName = 5415;
@@ -984,6 +984,8 @@ void window_title_editor_scrollpaint(rct_window *w, rct_drawpixelinfo *dpi, int
 			case TITLE_SCRIPT_END:
 				commandName = 5426;
 				break;
+			default:
+				log_warning("Unknown command %d", command->command);
 			}
 
 			if ((selected || hover) && !error) {
diff --git a/src/windows/track_place.c b/src/windows/track_place.c
index c879b4907a..85365c9dc9 100644
--- a/src/windows/track_place.c
+++ b/src/windows/track_place.c
@@ -352,6 +352,7 @@ static void window_track_place_attempt_placement(int x, int y, int z, int bl, mo
 	int eax, ebx, ecx, edx, esi, edi, ebp;
 	money32 result;
 
+	edx = esi = ebp = 0;
 	eax = x;
 	ebx = bl;
 	ecx = y;