diff --git a/Makefile b/Makefile
index b21dfcb..c9a2c36 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC ?= gcc
 
 CFLAGS+=-Wall -Wextra -pedantic
-SANITY_FLAGS=-Wfloat-equal -Wshadow -Wpointer-arith
+SANITY_FLAGS=-Wfloat-equal -Wshadow -Wpointer-arith -Wstrict-prototypes
 
 PREFIX ?= /usr
 
diff --git a/src/arm/soc.c b/src/arm/soc.c
index 882f2f9..f434e48 100644
--- a/src/arm/soc.c
+++ b/src/arm/soc.c
@@ -618,7 +618,7 @@ struct system_on_chip* guess_soc_from_cpuinfo(struct system_on_chip* soc) {
   return soc;
 }
 
-char* get_rk_efuse() {
+char* get_rk_efuse(void) {
   int filelen;
   char* rk_soc = read_file(_PATH_RK_EFUSE0, &filelen);
   if(rk_soc == NULL) {
diff --git a/src/riscv/udev.c b/src/riscv/udev.c
index 1769e9e..1549fdd 100644
--- a/src/riscv/udev.c
+++ b/src/riscv/udev.c
@@ -86,7 +86,7 @@ char* get_uarch_from_cpuinfo(void) {
   return parse_cpuinfo_field(CPUINFO_UARCH_STR);
 }
 
-char* get_extensions_from_cpuinfo() {
+char* get_extensions_from_cpuinfo(void) {
   return parse_cpuinfo_field(CPUINFO_EXTENSIONS_STR);
 }