diff --git a/INSTALL.md b/INSTALL.md
index fcdd8b655..8825e49da 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -101,3 +101,16 @@ If you've only changed `.c` or `.s` files, you can turn off the dependency scann
 
 `make NODEP=1`
 
+# Building with devkitARM's C compiler
+
+This project supports the `arm-none-eabi-gcc` compiler which ships with devkitARM r52.  To build this target, simply run:
+
+    make modern
+
+# Building with your own toolchain
+
+To build Pokemon Emerald with a toolchain other than devkitARM, override the `DEVKITARM` environment variable with the path to your toolchain.  Example:
+
+    make compare DEVKITARM=/usr/local/arm-none-eabi
+
+The path you pass to the `DEVKITARM` variable must contain the subdirectory `bin`.  If you compile the `modern` target with this toolchain, the subdirectories `lib`, `include`, and `arm-none-eabi` must also be present.
diff --git a/Makefile b/Makefile
index a47c45135..1f974c770 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,11 @@
+ifneq (,$(wildcard $(DEVKITARM)/base_tools))
 include $(DEVKITARM)/base_tools
+else
+PREFIX := $(DEVKITARM)/bin/arm-none-eabi-
+OBJCOPY := $(PREFIX)objcopy
+CC := $(PREFIX)gcc
+AS := $(PREFIX)as
+endif
 export CPP := $(PREFIX)cpp
 export LD := $(PREFIX)ld
 
@@ -48,7 +55,14 @@ OBJ_DIR := build/modern
 LIBPATH := -L $(DEVKITARM)/lib/gcc/arm-none-eabi/*/thumb -L $(DEVKITARM)/arm-none-eabi/lib/thumb
 endif
 
-CPPFLAGS := -I tools/agbcc/include -I tools/agbcc -iquote include -Wno-trigraphs -DMODERN=$(MODERN)
+ifeq ($(DEBUG),1)
+CFLAGS += -g
+endif
+
+CPPFLAGS := -iquote include -Wno-trigraphs -DMODERN=$(MODERN)
+ifeq ($(MODERN),0)
+CPPFLAGS += -I tools/agbcc/include -I tools/agbcc
+endif
 
 LDFLAGS = -Map ../../$(MAP)
 
diff --git a/include/fieldmap.h b/include/fieldmap.h
index 2384ed46a..be5610a46 100644
--- a/include/fieldmap.h
+++ b/include/fieldmap.h
@@ -23,9 +23,9 @@ int GetMapBorderIdAt(int x, int y);
 int CanCameraMoveInDirection(int direction);
 u16 GetBehaviorByMetatileId(u16 metatileId);
 void GetCameraFocusCoords(u16 *x, u16 *y);
-u8 MapGridGetMetatileLayerTypeAt(s32 x, s32 y);
+u8 MapGridGetMetatileLayerTypeAt(int x, int y);
 u8 MapGridGetZCoordAt(int x, int y);
-u8 CameraMove(s32 deltaX, s32 deltaY);
+bool8 CameraMove(int deltaX, int deltaY);
 struct MapConnection *sub_8088950(u8 direction, int x, int y);
 bool8 sub_80889A8(u8 direction, int x, int y, struct MapConnection *connection);
 bool8 sub_8088A0C(int x, int src_width, int dest_width, int offset);
diff --git a/include/global.h b/include/global.h
index 712a40866..a76d6e4e3 100644
--- a/include/global.h
+++ b/include/global.h
@@ -2,6 +2,7 @@
 #define GUARD_GLOBAL_H
 
 #include <string.h>
+#include <limits.h>
 #include "config.h" // we need to define config before gba headers as print stuff needs the functions nulled before defines.
 #include "gba/gba.h"
 #include "constants/global.h"
diff --git a/include/link_rfu.h b/include/link_rfu.h
index dc5b963d1..4bf106ec1 100644
--- a/include/link_rfu.h
+++ b/include/link_rfu.h
@@ -278,7 +278,7 @@ bool32 sub_8011B90(void);
 void sub_800FE50(u16 *a0);
 bool32 sub_800E540(u16 id, u8 *name);
 void sub_8011DE0(u32 arg0);
-u8 sub_801100C(int a0);
+u8 sub_801100C(s32 a0);
 void sub_800EF7C(void);
 bool8 sub_800DE7C(struct UnkLinkRfuStruct_02022B14 *buff1, u8 *buff2, u8 idx);
 bool8 sub_800DF34(struct UnkLinkRfuStruct_02022B14 *buff1, u8 *buff2, u8 idx);