diff --git a/macros.mingw32 b/macros.mingw32
index 4a87dcf..924804b 100644
--- a/macros.mingw32
+++ b/macros.mingw32
@@ -63,11 +63,11 @@
   done; \
   unset _PREFIX; \
   CC="${MINGW32_CC:-%mingw32_cc}"; export CC; \
-  CFLAGS="${MINGW32_CFLAGS:-%mingw32_cflags}"; export CFLAGS; \
-  CPPFLAGS="${MINGW32_CPPFLAGS:-%mingw32_cppflags}"; export CPPFLAGS; \
+  CFLAGS="${MINGW32_CFLAGS-%mingw32_cflags}"; export CFLAGS; \
+  CPPFLAGS="${MINGW32_CPPFLAGS-%mingw32_cppflags}"; export CPPFLAGS; \
   if [ -x "%{_bindir}/%{mingw32_cxx}" ]; then \
     CXX="${MINGW32_CXX:-%mingw32_cxx}"; export CXX; \
-    CXXFLAGS="${MINGW32_CXXFLAGS:-%mingw32_cflags}"; export CXXFLAGS; \
+    CXXFLAGS="${MINGW32_CXXFLAGS-%mingw32_cflags}"; export CXXFLAGS; \
   else \
     CXX=; export CXX; \
     ac_cv_prog_CXX=no; export ac_cv_prog_CXX; \
diff --git a/macros.mingw64 b/macros.mingw64
index 8d18768..8db57f4 100644
--- a/macros.mingw64
+++ b/macros.mingw64
@@ -63,11 +63,11 @@
   done; \
   unset _PREFIX; \
   CC="${MINGW64_CC:-%mingw64_cc}"; export CC; \
-  CFLAGS="${MINGW64_CFLAGS:-%mingw64_cflags}"; export CFLAGS; \
-  CPPFLAGS="${MINGW64_CPPFLAGS:-%mingw64_cppflags}"; export CPPFLAGS; \
+  CFLAGS="${MINGW64_CFLAGS-%mingw64_cflags}"; export CFLAGS; \
+  CPPFLAGS="${MINGW64_CPPFLAGS-%mingw64_cppflags}"; export CPPFLAGS; \
   if [ -x "%{_bindir}/%{mingw64_cxx}" ]; then \
     CXX="${MINGW64_CXX:-%mingw64_cxx}"; export CXX; \
-    CXXFLAGS="${MINGW64_CXXFLAGS:-%mingw64_cflags}"; export CXXFLAGS; \
+    CXXFLAGS="${MINGW64_CXXFLAGS-%mingw64_cflags}"; export CXXFLAGS; \
   else \
     CXX=; export CXX; \
     ac_cv_prog_CXX=no; export ac_cv_prog_CXX; \
diff --git a/mingw-filesystem.spec b/mingw-filesystem.spec
index f645a88..4f78c33 100644
--- a/mingw-filesystem.spec
+++ b/mingw-filesystem.spec
@@ -330,6 +330,7 @@ install -m 0644 %{SOURCE12} $RPM_BUILD_ROOT%{_datadir}/mingw/
   * Don't set LIB_INSTALL_DIR any more in the CMake macros
     as it breaks CPack and isn't needed by any of the
     Fedora MinGW packages (RHBZ #1152696)
+- Accept empty MINGW{32,64}_{C,CPP,CXX}FLAGS environment variables
 
 * Sat Jun 07 2014 Fedora Release Engineering <rel-eng@lists.fedoraproject.org>
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_21_Mass_Rebuild