diff --git a/CMakeLists.txt b/CMakeLists.txt
index a75c86e6e..df03278a3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 2.6)
 project(GBAc)
-set(CMAKE_C_FLAGS_DEBUG "-g -Wall -Wextra -Wno-unused -Werror")
-set(CMAKE_C_FLAGS_RELEASE "-O3 -Wall -Wextra -Wno-unused -Werror")
+set(CMAKE_C_FLAGS_DEBUG "-g -Wall -Wextra -Wno-unused -Werror --std=gnu99")
+set(CMAKE_C_FLAGS_RELEASE "-O3 -Wall -Wextra -Wno-unused -Werror --std=gnu99")
 file(GLOB ARM_SRC ${CMAKE_SOURCE_DIR}/src/arm/*.c)
 file(GLOB GBA_SRC ${CMAKE_SOURCE_DIR}/src/gba/*.c)
 file(GLOB RENDERER_SRC ${CMAKE_SOURCE_DIR}/src/gba/renderers/*.c)
diff --git a/src/arm/isa-arm.c b/src/arm/isa-arm.c
index edf196aa0..ffb5b16b1 100644
--- a/src/arm/isa-arm.c
+++ b/src/arm/isa-arm.c
@@ -250,7 +250,7 @@ void ARMStep(struct ARMCore* cpu) {
 #define ADDR_MODE_3_ADDRESS ADDR_MODE_2_ADDRESS
 #define ADDR_MODE_3_RN ADDR_MODE_2_RN
 #define ADDR_MODE_3_RM ADDR_MODE_2_RM
-#define ADDR_MODE_3_IMMEDIATE ((opcode & 0x00000F00) >> 4) | (opcode & 0x0000000F)
+#define ADDR_MODE_3_IMMEDIATE (((opcode & 0x00000F00) >> 4) | (opcode & 0x0000000F))
 #define ADDR_MODE_3_INDEX(U_OP, M) ADDR_MODE_2_INDEX(U_OP, M)
 #define ADDR_MODE_3_WRITEBACK(ADDR) ADDR_MODE_2_WRITEBACK(ADDR)
 
diff --git a/src/arm/isa-thumb.c b/src/arm/isa-thumb.c
index 37372a13f..64e41fd89 100644
--- a/src/arm/isa-thumb.c
+++ b/src/arm/isa-thumb.c
@@ -281,8 +281,8 @@ DEFINE_DATA_FORM_5_INSTRUCTION_THUMB(MVN, cpu->gprs[rd] = ~cpu->gprs[rn]; THUMB_
 
 #define DEFINE_INSTRUCTION_WITH_HIGH_EX_THUMB(NAME, H1, H2, BODY) \
 	DEFINE_INSTRUCTION_THUMB(NAME, \
-		int rd = opcode & 0x0007 | H1; \
-		int rm = (opcode >> 3) & 0x0007 | H2; \
+		int rd = (opcode & 0x0007) | H1; \
+		int rm = ((opcode >> 3) & 0x0007) | H2; \
 		BODY;)
 
 #define DEFINE_INSTRUCTION_WITH_HIGH_THUMB(NAME, BODY) \
@@ -461,7 +461,7 @@ DEFINE_INSTRUCTION_THUMB(BX,
 	if (rm == ARM_PC) {
 		misalign = cpu->gprs[rm] & 0x00000002;
 	}
-	cpu->gprs[ARM_PC] = cpu->gprs[rm] & 0xFFFFFFFE - misalign;
+	cpu->gprs[ARM_PC] = (cpu->gprs[rm] & 0xFFFFFFFE) - misalign;
 	if (cpu->executionMode == MODE_THUMB) {
 		THUMB_WRITE_PC;
 	} else {
diff --git a/src/debugger/debugger.c b/src/debugger/debugger.c
index 651ae6f5e..71e90c895 100644
--- a/src/debugger/debugger.c
+++ b/src/debugger/debugger.c
@@ -6,7 +6,7 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdlib.h>
-#include <strings.h>
+#include <string.h>
 #include <unistd.h>
 #include "linenoise.h"
 
diff --git a/src/gba/gba-bios.c b/src/gba/gba-bios.c
index 7b21d2dc9..8c43b32dc 100644
--- a/src/gba/gba-bios.c
+++ b/src/gba/gba-bios.c
@@ -5,6 +5,7 @@
 #include "gba-memory.h"
 
 #include <math.h>
+#include <stdlib.h>
 
 static void _unLz77(struct GBAMemory* memory, uint32_t source, uint8_t* dest);
 
diff --git a/src/gba/gba-video.c b/src/gba/gba-video.c
index 4ba717af5..8b9a80192 100644
--- a/src/gba/gba-video.c
+++ b/src/gba/gba-video.c
@@ -161,6 +161,5 @@ static void GBAVideoDummyRendererDrawScanline(struct GBAVideoRenderer* renderer,
 
 static void GBAVideoDummyRendererFinishFrame(struct GBAVideoRenderer* renderer) {
 	(void)(renderer);
-	printf("Drawing a frame\n");
 	// Nothing to do
 }
diff --git a/src/gba/gba.c b/src/gba/gba.c
index f03cfceb9..3cd5b706d 100644
--- a/src/gba/gba.c
+++ b/src/gba/gba.c
@@ -228,7 +228,7 @@ void GBAAttachDebugger(struct GBA* gba, struct ARMDebugger* debugger) {
 }
 
 void GBALoadROM(struct GBA* gba, int fd) {
-	gba->memory.rom = mmap(0, SIZE_CART0, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FILE, fd, 0);
+	gba->memory.rom = mmap(0, SIZE_CART0, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 	// TODO: error check
 }
 
diff --git a/src/gba/renderers/video-software.c b/src/gba/renderers/video-software.c
index 85ebdb2a4..d4aa58147 100644
--- a/src/gba/renderers/video-software.c
+++ b/src/gba/renderers/video-software.c
@@ -18,7 +18,8 @@ static void GBAVideoSoftwareRendererWriteBLDCNT(struct GBAVideoSoftwareRenderer*
 
 static void _compositeBackground(struct GBAVideoSoftwareRenderer* renderer, int offset, int entry, struct PixelFlags flags);
 static void _drawBackgroundMode0(struct GBAVideoSoftwareRenderer* renderer, struct GBAVideoSoftwareBackground* background, int y);
-static void _drawSprite(struct GBAVideoSoftwareRenderer* renderer, struct GBAObj* spritem, int y);
+static void _drawTransformedSprite(struct GBAVideoSoftwareRenderer* renderer, struct GBATransformedObj* sprite, int y);
+static void _drawSprite(struct GBAVideoSoftwareRenderer* renderer, struct GBAObj* sprite, int y);
 
 static void _updatePalettes(struct GBAVideoSoftwareRenderer* renderer);
 static inline uint16_t _brighten(uint16_t color, int y);
diff --git a/src/main.c b/src/main.c
index db86bfaff..74e07a784 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3,8 +3,12 @@
 #include "gba.h"
 #include "renderers/video-software.h"
 
-#include <sdl.h>
+#include <SDL.h>
+#ifdef __APPLE__
 #include <OpenGL/gl.h>
+#else
+#include <GL/gl.h>
+#endif
 
 #include <fcntl.h>
 #include <errno.h>