diff --git a/cfastmanifest/tree.h b/cfastmanifest/tree.h
index f0b8a0ce0b..6fb2d41fec 100644
--- a/cfastmanifest/tree.h
+++ b/cfastmanifest/tree.h
@@ -59,7 +59,7 @@ typedef struct _iterator_t iterator_t;
  */
 extern bool valid_path(const char *path, const size_t path_sz);
 
-extern tree_t *alloc_tree();
+extern tree_t *alloc_tree(void);
 
 extern void destroy_tree(tree_t *tree);
 
diff --git a/cfastmanifest/tree_disk.c b/cfastmanifest/tree_disk.c
index d83b99f89d..841eb63ca9 100644
--- a/cfastmanifest/tree_disk.c
+++ b/cfastmanifest/tree_disk.c
@@ -62,7 +62,7 @@ typedef struct _v0_header_t {
 /**
  * Returns true iff the host is little endian.
  */
-static inline bool little_endian() {
+static inline bool little_endian(void) {
   int foo = LITTLE_ENDIAN_TEST_VALUE;
   if (ntohl(foo) == LITTLE_ENDIAN_TEST_VALUE) {
     return false;
@@ -74,7 +74,7 @@ static inline bool little_endian() {
 /**
  * Returns the size, in bytes, of the host pointer.
  */
-static inline uint8_t host_pointer_size() {
+static inline uint8_t host_pointer_size(void) {
   return sizeof(void*);
 }
 
diff --git a/setup.py b/setup.py
index 3d39011352..f14629f8d8 100644
--- a/setup.py
+++ b/setup.py
@@ -85,7 +85,10 @@ setup(
                   ],
                   libraries=['crypto',
                   ],
-                  extra_compile_args=["-std=c99", "-Wall", "-Werror"],
+                  extra_compile_args=[
+                      "-std=c99",
+                      "-Wall",
+                      "-Werror", "-Werror=strict-prototypes"],
         )
     ],
 )