diff --git a/src/common.h b/src/common.h
index d17bf1cee..3d1f0e581 100644
--- a/src/common.h
+++ b/src/common.h
@@ -8,12 +8,17 @@
 #ifdef GIT_HAS_PTHREAD
 # include <pthread.h>
 #endif
+#include <inttypes.h>
 #include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <string.h>
 
+#ifndef PRIuPTR
+# define PRIuPTR "lu"
+#endif
+
 #include "git/common.h"
 
 #define GIT_PATH_MAX 4096
diff --git a/src/odb.c b/src/odb.c
index 32a550a02..c8df02975 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -88,7 +88,7 @@ int git_obj__loose_object_type(git_otype type)
 static int format_object_header(char *hdr, size_t n, git_obj *obj)
 {
 	const char *type_str = git_obj_type_to_string(obj->type);
-	int len = snprintf(hdr, n, "%s %u", type_str, obj->len);
+	int len = snprintf(hdr, n, "%s %" PRIuPTR, type_str, obj->len);
 
 	assert(len > 0);  /* otherwise snprintf() is broken */
 	assert(len < n);  /* otherwise the caller is broken! */