diff --git a/libavcodec/dct-test.c b/libavcodec/dct-test.c
index 3f62f6d633..f47696251a 100644
--- a/libavcodec/dct-test.c
+++ b/libavcodec/dct-test.c
@@ -48,7 +48,7 @@ void *fast_memcpy(void *a, const void *b, size_t c){return memcpy(a,b,c);};
 /* reference fdct/idct */
 void fdct(DCTELEM *block);
 void idct(DCTELEM *block);
-void init_fdct();
+void init_fdct(void);
 
 void ff_mmx_idct(DCTELEM *data);
 void ff_mmxext_idct(DCTELEM *data);
diff --git a/libavcodec/faxcompr.c b/libavcodec/faxcompr.c
index e7f7706b94..f6158ca6d8 100644
--- a/libavcodec/faxcompr.c
+++ b/libavcodec/faxcompr.c
@@ -95,7 +95,7 @@ static const uint8_t ccitt_group3_2d_lens[11] = {
 
 static VLC ccitt_vlc[2], ccitt_group3_2d_vlc;
 
-av_cold void ff_ccitt_unpack_init()
+av_cold void ff_ccitt_unpack_init(void)
 {
     static VLC_TYPE code_table1[528][2];
     static VLC_TYPE code_table2[648][2];
diff --git a/libavcodec/faxcompr.h b/libavcodec/faxcompr.h
index 632744be64..9eb3485b02 100644
--- a/libavcodec/faxcompr.h
+++ b/libavcodec/faxcompr.h
@@ -33,7 +33,7 @@
 /**
  * initialize upacker code
  */
-void ff_ccitt_unpack_init();
+void ff_ccitt_unpack_init(void);
 
 /**
  * unpack data compressed with CCITT Group 3 1/2-D or Group 4 method
diff --git a/libavcodec/fdctref.c b/libavcodec/fdctref.c
index c6a057b846..119d23f787 100644
--- a/libavcodec/fdctref.c
+++ b/libavcodec/fdctref.c
@@ -46,7 +46,7 @@ void fdct (short *block);
 /* private data */
 static double c[8][8]; /* transform coefficients */
 
-void init_fdct()
+void init_fdct(void)
 {
   int i, j;
   double s;
diff --git a/libavcodec/mlp.c b/libavcodec/mlp.c
index 6f10c3535e..c522617e0b 100644
--- a/libavcodec/mlp.c
+++ b/libavcodec/mlp.c
@@ -46,7 +46,7 @@ static AVCRC crc_63[1024];
 static AVCRC crc_1D[1024];
 static AVCRC crc_2D[1024];
 
-void av_cold ff_mlp_init_crc()
+av_cold void ff_mlp_init_crc(void)
 {
     if (!crc_init) {
         av_crc_init(crc_63, 0,  8,   0x63, sizeof(crc_63));
diff --git a/libavcodec/mlp.h b/libavcodec/mlp.h
index b81c735d1f..032a8f6bdf 100644
--- a/libavcodec/mlp.h
+++ b/libavcodec/mlp.h
@@ -106,7 +106,7 @@ uint8_t ff_mlp_restart_checksum(const uint8_t *buf, unsigned int bit_size);
  */
 uint8_t ff_mlp_calculate_parity(const uint8_t *buf, unsigned int buf_size);
 
-void ff_mlp_init_crc();
+void ff_mlp_init_crc(void);
 
 /** XOR four bytes into one. */
 static inline uint8_t xor_32_to_8(uint32_t value)
diff --git a/libavcodec/mlpdec.c b/libavcodec/mlpdec.c
index f4323da542..a9f69488fc 100644
--- a/libavcodec/mlpdec.c
+++ b/libavcodec/mlpdec.c
@@ -141,7 +141,7 @@ static VLC huff_vlc[3];
 
 /** Initialize static data, constant between all invocations of the codec. */
 
-static av_cold void init_static()
+static av_cold void init_static(void)
 {
     INIT_VLC_STATIC(&huff_vlc[0], VLC_BITS, 18,
                 &ff_mlp_huffman_tables[0][0][1], 2, 1,
diff --git a/libavcodec/mpc.c b/libavcodec/mpc.c
index 596a5e9f34..764afd65d3 100644
--- a/libavcodec/mpc.c
+++ b/libavcodec/mpc.c
@@ -36,7 +36,7 @@
 
 static DECLARE_ALIGNED_16(MPA_INT, mpa_window[512]);
 
-void ff_mpc_init()
+void ff_mpc_init(void)
 {
     ff_mpa_synth_init(mpa_window);
 }
diff --git a/libavcodec/mpc.h b/libavcodec/mpc.h
index df33683687..215c96b13b 100644
--- a/libavcodec/mpc.h
+++ b/libavcodec/mpc.h
@@ -70,7 +70,7 @@ typedef struct {
     DECLARE_ALIGNED_16(int32_t, sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT]);
 } MPCContext;
 
-void ff_mpc_init();
+void ff_mpc_init(void);
 void ff_mpc_dequantize_and_synth(MPCContext *c, int maxband, void *dst);
 
 #endif /* AVCODEC_MPC_H */
diff --git a/libavcodec/rv34.c b/libavcodec/rv34.c
index 5de62daa4f..ca1db04b3c 100644
--- a/libavcodec/rv34.c
+++ b/libavcodec/rv34.c
@@ -101,7 +101,7 @@ static void rv34_gen_vlc(const uint8_t *bits, int size, VLC *vlc, const uint8_t
 /**
  * Initialize all tables.
  */
-static av_cold void rv34_init_tables()
+static av_cold void rv34_init_tables(void)
 {
     int i, j, k;
 
diff --git a/libavcodec/rv40.c b/libavcodec/rv40.c
index 083de1b14e..6b9183af3e 100644
--- a/libavcodec/rv40.c
+++ b/libavcodec/rv40.c
@@ -40,7 +40,7 @@ static VLC ptype_vlc[NUM_PTYPE_VLCS], btype_vlc[NUM_BTYPE_VLCS];
 /**
  * Initialize all tables.
  */
-static av_cold void rv40_init_tables()
+static av_cold void rv40_init_tables(void)
 {
     int i;
 
diff --git a/libavcodec/sparc/dsputil_vis.c b/libavcodec/sparc/dsputil_vis.c
index 0779395986..92c868cafa 100644
--- a/libavcodec/sparc/dsputil_vis.c
+++ b/libavcodec/sparc/dsputil_vis.c
@@ -3988,7 +3988,7 @@ static void MC_avg_no_round_xy_8_vis (uint8_t * dest, const uint8_t * _ref,
 #define ACCEL_SPARC_VIS 1
 #define ACCEL_SPARC_VIS2 2
 
-static int vis_level ()
+static int vis_level(void)
 {
     int accel = 0;
     accel |= ACCEL_SPARC_VIS;