diff --git a/sys-power/iasl/patches/acpica-haiku.diff b/sys-power/iasl/patches/acpica-haiku.diff
new file mode 100644
index 000000000..a1d4dd99f
--- /dev/null
+++ b/sys-power/iasl/patches/acpica-haiku.diff
@@ -0,0 +1,31 @@
+Index: compiler/Makefile
+===================================================================
+--- compiler/Makefile	(revision 41258)
++++ compiler/Makefile	(working copy)
+@@ -12,7 +12,7 @@
+ ACPICA_OSL =    $(ACPICA_SRC)/os_specific/service_layers
+ 
+ NOMAN=	YES
+-CFLAGS+= -Wall -O2 -Wstrict-prototypes -D_LINUX -DACPI_ASL_COMPILER -I../include -I../compiler
++CFLAGS+= -Wall -O2 -Wstrict-prototypes -DACPI_ASL_COMPILER -I../include -I../compiler
+ 
+ #
+ # Bison/Flex configuration
+@@ -25,9 +25,16 @@
+ 
+ 
+ COMPILE = $(CC) -c $(CFLAGS) -o$@ $?
++
++OS ?= Linux
++ifeq ($(OS),Linux)
++CFLAGS += -D_LINUX
+ LDFLAGS += -lpthread -lrt
++endif
++ifeq ($(OS),Haiku)
++CFLAGS += -D_LINUX
++endif
+ 
+-
+ OBJS = \
+ 	adfile.o \
+ 	adisasm.o \