diff --git a/tools/Makefile b/tools/Makefile
index 469a0191..1ac9c8cb 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -10,6 +10,20 @@ LDFLAGS      := -lm
 ALL_PROGRAMS := n64graphics n64graphics_ci mio0 n64cksum textconv patch_libultra_math aifc_decode aiff_extract_codebook vadpcm_enc tabledesign extract_data_for_mio skyconv
 LIBAUDIOFILE := audiofile/libaudiofile.a
 
+# Attempt to detect OS
+ifeq ($(OS),Windows_NT)
+  HOST_OS ?= Windows
+else
+  HOST_OS ?= $(shell uname -s 2>/dev/null || echo Unknown)
+  # some weird MINGW/Cygwin env that doesn't define $OS
+  ifneq (,$(findstring MINGW,HOST_OS))
+    HOST_OS := Windows
+  endif
+endif
+ifeq ($(HOST_OS),Windows)
+  CFLAGS += -DWIN32 -D_WIN32 -D__CYGWIN__
+endif
+
 BUILD_PROGRAMS := $(ALL_PROGRAMS)
 
 default: all
diff --git a/tools/audiofile/Makefile b/tools/audiofile/Makefile
index 8a11925e..5e204324 100644
--- a/tools/audiofile/Makefile
+++ b/tools/audiofile/Makefile
@@ -1,11 +1,27 @@
 CXX := g++
 
+CFLAGS :=
+
+# Attempt to detect OS
+ifeq ($(OS),Windows_NT)
+  HOST_OS ?= Windows
+else
+  HOST_OS ?= $(shell uname -s 2>/dev/null || echo Unknown)
+  # some weird MINGW/Cygwin env that doesn't define $OS
+  ifneq (,$(findstring MINGW,HOST_OS))
+    HOST_OS := Windows
+  endif
+endif
+ifeq ($(HOST_OS),Windows)
+  CFLAGS += -DWIN32 -D_WIN32 -D__CYGWIN__
+endif
+
 libaudiofile.a: audiofile.o
 	$(AR) rcs $@ $^
 
 audiofile.o: audiofile.cpp audiofile.h aupvlist.h
-	#$(CXX) -std=c++11 -DNDEBUG -fno-rtti -fno-exceptions -fvisibility-inlines-hidden -O2 -I. -c audiofile.cpp
-	$(CXX) -std=c++11 -O2 -I. -c $< -o $@
+	#$(CXX) $(CFLAGS) -std=c++11 -DNDEBUG -fno-rtti -fno-exceptions -fvisibility-inlines-hidden -O2 -I. -c audiofile.cpp
+	$(CXX) $(CFLAGS) -std=c++11 -O2 -I. -c $< -o $@
 
 clean:
 	$(RM) audiofile.o libaudiofile.a
diff --git a/tools/sdk-tools/adpcm/Makefile b/tools/sdk-tools/adpcm/Makefile
index b97991be..9fee76d1 100644
--- a/tools/sdk-tools/adpcm/Makefile
+++ b/tools/sdk-tools/adpcm/Makefile
@@ -8,6 +8,20 @@ IRIX_CFLAGS := -fullwarn -woff 515,608,658,799 -Wab,-r4300_mul -g -Xcpluscomm -m
 NATIVE_CC := gcc
 NATIVE_CFLAGS := -g -Wall -O2 -Wno-unused-result -Wno-uninitialized
 
+# Attempt to detect OS
+ifeq ($(OS),Windows_NT)
+  HOST_OS ?= Windows
+else
+  HOST_OS ?= $(shell uname -s 2>/dev/null || echo Unknown)
+  # some weird MINGW/Cygwin env that doesn't define $OS
+  ifneq (,$(findstring MINGW,HOST_OS))
+    HOST_OS := Windows
+  endif
+endif
+ifeq ($(HOST_OS),Windows)
+  NATIVE_CFLAGS += -DWIN32 -D_WIN32 -D__CYGWIN__
+endif
+
 default: native
 all: irix native
 
diff --git a/tools/sdk-tools/tabledesign/Makefile b/tools/sdk-tools/tabledesign/Makefile
index a06d70af..afd0a92e 100644
--- a/tools/sdk-tools/tabledesign/Makefile
+++ b/tools/sdk-tools/tabledesign/Makefile
@@ -8,6 +8,20 @@ IRIX_CFLAGS := -fullwarn -Wab,-r4300_mul -Xcpluscomm -mips1 -O2
 NATIVE_CC := gcc
 NATIVE_CFLAGS := -Wall -Wno-uninitialized -O2
 
+# Attempt to detect OS
+ifeq ($(OS),Windows_NT)
+  HOST_OS ?= Windows
+else
+  HOST_OS ?= $(shell uname -s 2>/dev/null || echo Unknown)
+  # some weird MINGW/Cygwin env that doesn't define $OS
+  ifneq (,$(findstring MINGW,HOST_OS))
+    HOST_OS := Windows
+  endif
+endif
+ifeq ($(HOST_OS),Windows)
+  NATIVE_CFLAGS += -DWIN32 -D_WIN32 -D__CYGWIN__
+endif
+
 LDFLAGS := -lm -laudiofile
 
 default: native