diff --git a/src/configure b/src/configure
index ed1af281db..84f8cddb4f 100755
--- a/src/configure
+++ b/src/configure
@@ -5201,7 +5201,7 @@ echo "${ECHO_T}$have_libffi" >&6; }
   else
     CFLAGS="${OLD_CFLAGS}"
     PREFLAGS="${PREFLAGS} ${libffi_config_preflags}"
-    CFLAGS="${COMPFLAGS} ${libffi_config_cflags}"
+    COMPFLAGS="${COMPFLAGS} ${libffi_config_cflags}"
     echo "Using installed libffi"
     OWN_LIBFFI="OFF"
   fi
diff --git a/src/racket/configure.ac b/src/racket/configure.ac
index 270737f6ce..6fe1caf674 100644
--- a/src/racket/configure.ac
+++ b/src/racket/configure.ac
@@ -896,7 +896,7 @@ if test "${enable_libffi}" = "yes" ; then
   else
     CFLAGS="${OLD_CFLAGS}"
     PREFLAGS="${PREFLAGS} ${libffi_config_preflags}"
-    CFLAGS="${COMPFLAGS} ${libffi_config_cflags}"
+    COMPFLAGS="${COMPFLAGS} ${libffi_config_cflags}"
     echo "Using installed libffi"
     OWN_LIBFFI="OFF"
   fi