diff --git a/Makefile b/Makefile
index b81760d..f95856f 100644
--- a/Makefile
+++ b/Makefile
@@ -156,7 +156,7 @@ PROG_OBJ := $(PROG_COMMON_OBJ) $(PROG_SPECIFIC_OBJ)
 
 # Generate autodetected configuration header
 programs/config.h:programs/detect.sh .prog-cflags
-	$(QUIET_GEN) CC=$(CC) $< > $@
+	$(QUIET_GEN) CC="$(CC)" CFLAGS="$(CFLAGS)" $< > $@
 
 # Compile program object files
 $(PROG_OBJ): %.o: %.c $(PROG_COMMON_HEADERS) $(COMMON_HEADERS) .prog-cflags
diff --git a/programs/detect.sh b/programs/detect.sh
index 0ba10b0..05bc3a3 100755
--- a/programs/detect.sh
+++ b/programs/detect.sh
@@ -17,7 +17,7 @@ check_function() {
 	echo "int main() { $funcname(); }" > "$tmpfile"
 	echo
 	echo "/* Is the $funcname() function available? */"
-	if $CC -x c $tmpfile -o /dev/null > /dev/null 2>&1; then
+	if $CC $CFLAGS -x c $tmpfile -o /dev/null > /dev/null 2>&1; then
 		echo "#define $macro 1"
 	else
 		echo "/* $macro is not set */"