diff --git a/libexec/login_otp/login_otp.c b/libexec/login_otp/login_otp.c
index bbc38b8..01d8969 100644
--- a/libexec/login_otp/login_otp.c
+++ b/libexec/login_otp/login_otp.c
@@ -29,6 +29,7 @@
 
 #include "cryb/impl.h"
 
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
diff --git a/pam/pam_otp/pam_otp.c b/pam/pam_otp/pam_otp.c
index 147f776..b66dd31 100644
--- a/pam/pam_otp/pam_otp.c
+++ b/pam/pam_otp/pam_otp.c
@@ -31,6 +31,7 @@
 
 #define PAM_SM_AUTH
 
+#include <stddef.h>
 #include <stdint.h>
 
 #include <security/pam_modules.h>
diff --git a/sbin/otpradiusd/otpradiusd.c b/sbin/otpradiusd/otpradiusd.c
index ace58c8..0df5a40 100644
--- a/sbin/otpradiusd/otpradiusd.c
+++ b/sbin/otpradiusd/otpradiusd.c
@@ -29,6 +29,7 @@
 
 #include "cryb/impl.h"
 
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
diff --git a/t/t_cxx.cc b/t/t_cxx.cc
index 80dffa6..03a5481 100644
--- a/t/t_cxx.cc
+++ b/t/t_cxx.cc
@@ -58,6 +58,7 @@ public:
 	};
 
 #if WITH_CRYB_OTP
+#include <cryb/oath.h>
 #include <cryb/otp.h>
 TEST(otp)
 #endif