diff --git a/tools_common.c b/tools_common.c
index 7e2221712..901734e0f 100644
--- a/tools_common.c
+++ b/tools_common.c
@@ -170,7 +170,7 @@ static const VpxInterface vpx_decoders[] = {
 #endif
 };
 
-int get_vpx_decoder_count() {
+int get_vpx_decoder_count(void) {
   return sizeof(vpx_decoders) / sizeof(vpx_decoders[0]);
 }
 
diff --git a/tools_common.h b/tools_common.h
index db6e268a8..a87e814c1 100644
--- a/tools_common.h
+++ b/tools_common.h
@@ -135,7 +135,7 @@ int get_vpx_encoder_count(void);
 const VpxInterface *get_vpx_encoder_by_index(int i);
 const VpxInterface *get_vpx_encoder_by_name(const char *name);
 
-int get_vpx_decoder_count();
+int get_vpx_decoder_count(void);
 const VpxInterface *get_vpx_decoder_by_index(int i);
 const VpxInterface *get_vpx_decoder_by_name(const char *name);
 const VpxInterface *get_vpx_decoder_by_fourcc(uint32_t fourcc);