diff --git a/common/tools_common.h b/common/tools_common.h
index eeccbe4..b0b2367 100644
--- a/common/tools_common.h
+++ b/common/tools_common.h
@@ -157,7 +157,7 @@
 // The AOM library can support different encoders / decoders. These
 // functions provide different ways to lookup / iterate through them.
 // The return result may be NULL to indicate no codec was found.
-int get_aom_encoder_count();
+int get_aom_encoder_count(void);
 aom_codec_iface_t *get_aom_encoder_by_index(int i);
 aom_codec_iface_t *get_aom_encoder_by_short_name(const char *name);
 // If the interface is unknown, returns NULL.
@@ -165,7 +165,7 @@
 // If the interface is unknown, returns 0.
 uint32_t get_fourcc_by_aom_encoder(aom_codec_iface_t *iface);
 
-int get_aom_decoder_count();
+int get_aom_decoder_count(void);
 aom_codec_iface_t *get_aom_decoder_by_index(int i);
 aom_codec_iface_t *get_aom_decoder_by_short_name(const char *name);
 aom_codec_iface_t *get_aom_decoder_by_fourcc(uint32_t fourcc);