diff --git a/libretro-common/formats/png/rpng.c b/libretro-common/formats/png/rpng.c
index 4d537016d1..62f12a6f8a 100644
--- a/libretro-common/formats/png/rpng.c
+++ b/libretro-common/formats/png/rpng.c
@@ -52,7 +52,7 @@ enum image_process_code
    IMAGE_PROCESS_END       =  1,
 };
 
-enum png_chunk_type png_chunk_type(const struct png_chunk *chunk)
+static enum png_chunk_type png_chunk_type(const struct png_chunk *chunk)
 {
    unsigned i;
    struct
@@ -75,7 +75,7 @@ enum png_chunk_type png_chunk_type(const struct png_chunk *chunk)
    return PNG_CHUNK_NOOP;
 }
 
-bool png_process_ihdr(struct png_ihdr *ihdr)
+static bool png_process_ihdr(struct png_ihdr *ihdr)
 {
    unsigned i;
    bool ret = true;
@@ -589,7 +589,7 @@ static int png_reverse_filter_adam7(uint32_t **data_,
    return ret;
 }
 
-int png_reverse_filter_iterate(rpng_t *rpng, uint32_t **data)
+static int png_reverse_filter_iterate(rpng_t *rpng, uint32_t **data)
 {
    if (!rpng)
       return false;
@@ -659,7 +659,7 @@ false_end:
    return -1;
 }
 
-bool png_read_plte(uint8_t *buf, 
+static bool png_read_plte(uint8_t *buf, 
       uint32_t *buffer, unsigned entries)
 {
    unsigned i;
@@ -686,7 +686,7 @@ bool png_realloc_idat(const struct png_chunk *chunk, struct idat_buffer *buf)
    return true;
 }
 
-bool rpng_load_image_argb_process_init(rpng_t *rpng,
+static bool rpng_load_image_argb_process_init(rpng_t *rpng,
       uint32_t **data, unsigned *width, unsigned *height)
 {
    rpng->process.inflate_buf_size = 0;