diff --git a/tools/export/iar/__init__.py b/tools/export/iar/__init__.py
index e3fa360afd..3b60d11e4c 100644
--- a/tools/export/iar/__init__.py
+++ b/tools/export/iar/__init__.py
@@ -111,6 +111,8 @@ class IAR(Exporter):
                self.resources.c_sources + self.resources.cpp_sources + \
                self.resources.objects + self.resources.libraries
         flags = self.flags
+        _, macros = self.toolchain.config.get_config_data()
+        defines = ['-D%s' % d for d in macros] if macros else [""]
         c_flags = list(set(flags['common_flags']
                                     + flags['c_flags']
                                     + flags['cxx_flags']))
@@ -133,7 +135,8 @@ class IAR(Exporter):
             'include_paths': [self.format_file(src) for src in self.resources.inc_dirs],
             'device': self.iar_device(),
             'ewp': sep+self.project_name + ".ewp",
-            'debugger': debugger
+            'debugger': debugger,
+            'defines': defines
         }
         ctx.update(flags)
 
@@ -200,5 +203,3 @@ class IAR(Exporter):
             return -1
         else:
             return 0
-
-
diff --git a/tools/export/iar/ewp.tmpl b/tools/export/iar/ewp.tmpl
index cf5b7f0e6e..5b769ade6a 100644
--- a/tools/export/iar/ewp.tmpl
+++ b/tools/export/iar/ewp.tmpl
@@ -479,7 +479,9 @@
 				</option>
 				<option>
 					<name>ADefines</name>
-					<state></state>
+					{% for d in defines %}
+					<state>{{d}}</state>
+					{% endfor %}
 				</option>
 				<option>
 					<name>AList</name>
diff --git a/tools/toolchains/iar.py b/tools/toolchains/iar.py
index 99791bd89e..842db05186 100644
--- a/tools/toolchains/iar.py
+++ b/tools/toolchains/iar.py
@@ -154,8 +154,10 @@ class IAR(mbedToolchain):
 
     @hook_tool
     def assemble(self, source, object, includes):
+        _, macros = self.config.get_config_data()
+        defines = ['-D%s' % d for d in macros] if macros else [""]
         # Build assemble command
-        cmd = self.asm + self.get_compile_options(self.get_symbols(True), includes, True) + ["-o", object, source]
+        cmd = self.asm + self.get_compile_options(self.get_symbols(True), includes, True) + defines + ["-o", object, source]
 
         # Call cmdline hook
         cmd = self.hook.get_cmdline_assembler(cmd)