diff --git a/tools/fpga_compress/fpga_compress.c b/tools/fpga_compress/fpga_compress.c
index 56dab1865..0992c53ca 100644
--- a/tools/fpga_compress/fpga_compress.c
+++ b/tools/fpga_compress/fpga_compress.c
@@ -74,7 +74,7 @@ static bool all_feof(FILE *infile[], uint8_t num_infiles) {
 }
 
 
-int zlib_compress(FILE *infile[], uint8_t num_infiles, FILE *outfile, bool hardnested_mode) {
+static int zlib_compress(FILE *infile[], uint8_t num_infiles, FILE *outfile, bool hardnested_mode) {
     uint8_t *fpga_config;
     uint32_t i;
     int32_t ret;
@@ -184,7 +184,7 @@ int zlib_compress(FILE *infile[], uint8_t num_infiles, FILE *outfile, bool hardn
 }
 
 
-int zlib_decompress(FILE *infile, FILE *outfile) {
+static int zlib_decompress(FILE *infile, FILE *outfile) {
 #define DECOMPRESS_BUF_SIZE 1024
     uint8_t outbuf[DECOMPRESS_BUF_SIZE];
     uint8_t inbuf[DECOMPRESS_BUF_SIZE];