diff --git a/m4/fp_gcc_version.m4 b/m4/fp_gcc_version.m4
index df581a69f4e4bd152b6cf1fad55d996d41ef582c..c1a7f8c5b748188d1549ab0dd60c55808bf4bb49 100644
--- a/m4/fp_gcc_version.m4
+++ b/m4/fp_gcc_version.m4
@@ -8,7 +8,7 @@ AC_DEFUN([FP_GCC_VERSION], [
     AC_MSG_ERROR([C compiler is required])
   fi
 
-  if $CC --version | grep -q gcc; then
+  if $CC --version | grep -qi gcc; then
     AC_CACHE_CHECK([version of gcc], [fp_cv_gcc_version],
     [
         # Be sure only to look at the first occurrence of the "version " string;