diff --git a/internal/ossl/api.h b/internal/ossl/api.h
index e96919a0..828b6064 100644
--- a/internal/ossl/api.h
+++ b/internal/ossl/api.h
@@ -2,6 +2,7 @@
 
 #include "ossl.h"
 #include <stdint.h>
+#include <stddef.h>
 
 void ERR_clear_error(void);
 void ERR_error_string_n(unsigned long e, char *buf, size_t len);
diff --git a/internal/ossl/ossl_extra.h b/internal/ossl/ossl_extra.h
index dd1be420..e44234a2 100644
--- a/internal/ossl/ossl_extra.h
+++ b/internal/ossl/ossl_extra.h
@@ -1,5 +1,4 @@
 #include "api.h"
-#include <stddef.h>
 
 int go_openssl_fips_enabled(void* handle);
 int go_openssl_version_major(void* handle);