diff --git a/tools/export/sw4stm32/__init__.py b/tools/export/sw4stm32/__init__.py
index 4d6ebe6738..4d7ca53d5d 100644
--- a/tools/export/sw4stm32/__init__.py
+++ b/tools/export/sw4stm32/__init__.py
@@ -371,12 +371,9 @@ class Sw4STM32(GNUARMEclipse):
 
         preproc_cmd = ""
         # Hack for Windows. Build fails if command contains parentheses.
-        if ('(' in self.toolchain.preproc[0] or ')' in self.toolchain.preproc[0]) and self.toolchain.preproc[0][0] != "'":
-            preproc_cmd = '"' + \
-                self.toolchain.preproc[0] + '"' + " " + \
-                " ".join(self.toolchain.preproc[1:])
-        else:
-            preproc_cmd = " ".join(self.toolchain.preproc)
+        preproc_cmd = '"' + \
+            self.toolchain.preproc[0] + '"' + " " + \
+            " ".join(self.toolchain.preproc[1:])
 
         for id in ['debug', 'release']:
             opts = {}
diff --git a/tools/export/sw4stm32/makefile.targets.tmpl b/tools/export/sw4stm32/makefile.targets.tmpl
index 1cff1cd355..da87905d02 100644
--- a/tools/export/sw4stm32/makefile.targets.tmpl
+++ b/tools/export/sw4stm32/makefile.targets.tmpl
@@ -1,8 +1,6 @@
 # DO NOT REMOVE! Generated by the SW4STM32 exporter from the mbed project.
 
-ifeq ($(strip $(PREPROC_CMD)),)
-PREPROC_CMD := {{cpp_cmd}}
-endif
+PREPROC_CMD ?= {{cpp_cmd}}
 
 ldclean:
 {% for config, opts in options.iteritems() %}