diff --git a/src/cc-compat.h b/src/cc-compat.h
index 488de7f11..aefe66d19 100644
--- a/src/cc-compat.h
+++ b/src/cc-compat.h
@@ -30,6 +30,16 @@
 # define GIT_TYPEOF(x)
 #endif
 
+#ifdef __cplusplus
+# define GIT_UNUSED(x)
+#else
+# ifdef __GNUC__
+#  define GIT_UNUSED(x) x __attribute__ ((__unused__))
+# else
+#  define GIT_UNUSED(x) x
+# endif
+#endif
+
 /*
  * Does our compiler/platform support the C99 <inttypes.h> and
  * <stdint.h> header files. (C99 requires that <inttypes.h>
diff --git a/src/fileops.h b/src/fileops.h
index b5cc24e62..c5c58a0da 100644
--- a/src/fileops.h
+++ b/src/fileops.h
@@ -13,13 +13,13 @@
 #include <time.h>
 
 #ifdef GIT_WIN32
-GIT_INLINE(int) link(const char *old, const char *new)
+GIT_INLINE(int) link(const char *GIT_UNUSED(old), const char *GIT_UNUSED(new))
 {
 	errno = ENOSYS;
 	return -1;
 }
 
-GIT_INLINE(int) git__mkdir(const char *path, int mode)
+GIT_INLINE(int) git__mkdir(const char *path, int GIT_UNUSED(mode))
 {
 	return mkdir(path);
 }
diff --git a/src/odb.c b/src/odb.c
index 92ff64641..afadc73a3 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -1110,6 +1110,8 @@ static int read_packed(git_obj *out, git_pack *p, const git_oid *id)
 	off_t pos;
 	int res;
 
+	assert(out && p && id);
+
 	if (pack_openidx(p))
 		return GIT_ERROR;
 	res = p->idx_search(&pos, p, id);
@@ -1128,6 +1130,12 @@ int git_odb__read_packed(git_obj *out, git_odb *db, const git_oid *id)
 	git_packlist *pl = packlist_get(db);
 	size_t j;
 
+	assert(out && db && id);
+
+	out->data = NULL;
+	out->len  = 0;
+	out->type = GIT_OBJ_BAD;
+
 	if (!pl)
 		return GIT_ENOTFOUND;
 
diff --git a/tests/t0020-dirent.c b/tests/t0020-dirent.c
index a2e130b3f..334fff149 100644
--- a/tests/t0020-dirent.c
+++ b/tests/t0020-dirent.c
@@ -184,7 +184,7 @@ static walk_data empty = {
 	empty_names
 };
 
-static int dont_call_me(void *state, char *path)
+static int dont_call_me(void *GIT_UNUSED(state), char *GIT_UNUSED(path))
 {
 	test_die("dont_call_me: unexpected callback!");
 }