diff --git a/demos/asm/wscript b/demos/asm/wscript
index 9cd7c319..c56e7fe4 100644
--- a/demos/asm/wscript
+++ b/demos/asm/wscript
@@ -17,6 +17,7 @@ def build(bld):
 	bld.program(
 		source   = 'main.c test.S',
 		target   = 'asmtest',
+		defines  = 'foo=12',
 		includes = '.')
 
 	def disp(ctx):
diff --git a/waflib/Tools/asm.py b/waflib/Tools/asm.py
index 8619c460..46955c82 100644
--- a/waflib/Tools/asm.py
+++ b/waflib/Tools/asm.py
@@ -45,7 +45,7 @@ class asm(Task.Task):
 	Compile asm files by gas/nasm/yasm/...
 	"""
 	color = 'BLUE'
-	run_str = '${AS} ${ASFLAGS} ${ASMPATH_ST:INCPATHS} ${AS_SRC_F}${SRC} ${AS_TGT_F}${TGT}'
+	run_str = '${AS} ${ASFLAGS} ${ASMPATH_ST:INCPATHS} ${DEFINES_ST:DEFINES} ${AS_SRC_F}${SRC} ${AS_TGT_F}${TGT}'
 
 @extension('.s', '.S', '.asm', '.ASM', '.spp', '.SPP')
 def asm_hook(self, node):