diff --git a/INSTALL.md b/INSTALL.md
index 5981d899..cfb84688 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -5,6 +5,7 @@ Contents:
 - [Prerequisites](#prerequisites)
 - [Build the ROM](#build-the-rom)
     - [Matching the base ROM](#matching-the-base-rom)
+    - [Building with non-matching code](#building-with-non-matching-code)
 
 ## Prerequisites
 
@@ -55,3 +56,15 @@ ARM7 BIOS in the root directory of this repository, and verify that your dumped
 | `arm7_bios.bin` | `6ee830c7f552c5bf194c20a2c13d5bb44bdb5c03` |
 
 Now, `make` should automatically detect the ARM7 BIOS and will build a matching ROM.
+
+## Building with non-matching code
+Due to challenges with decompilation, some functions are not decompiled to 100% match the original assembly. Such functions are
+marked with `NONMATCH` before the function declaration.
+
+While non-matching functions do not contribute to getting a matching ROM, they can provide useful information (e.g. updates to
+structs/classes) or encourage collaboration to match the function.
+
+By default, non-matching functions are compiled with **inline assembly** so that the built ROM can still match the base ROM.
+However, by running `make NONMATCHING=1`, non-matching functions are compiled as **C++** instead of inline assembly.
+
+As a result, the built ROM will not match and is not guaranteed to function identically to the base ROM.
diff --git a/Makefile b/Makefile
index f051fa3d..1f433542 100644
--- a/Makefile
+++ b/Makefile
@@ -45,6 +45,10 @@ ASM_FLAGS := -proc arm5te -d $(REGION) -i asm -msgstyle gcc
 CC_FLAGS  := -O2 -enum int -i include -nolink -d $(REGION)
 LD_FLAGS  := -proc arm946e -nostdlib -interworking -nodead -m Entry -map closure,unused -o main.bin -msgstyle gcc
 
+ifeq ($(NONMATCHING),1)
+	CC_FLAGS += -DNONMATCHING
+endif
+
 .PHONY: all
 all: tools rom
 	sha1sum $(NDS_FILE)
diff --git a/include/global.h b/include/global.h
new file mode 100644
index 00000000..3201cd25
--- /dev/null
+++ b/include/global.h
@@ -0,0 +1,15 @@
+#ifndef PH_GLOBAL_H
+#define PH_GLOBAL_H
+
+#ifdef NONMATCHING
+#define NONMATCH
+#else
+#define NONMATCH asm
+#endif
+
+// Prevent the IDE from reporting errors that the compiler/linker won't report
+#ifdef __INTELLISENSE__
+#define NONMATCH
+#endif
+
+#endif