diff --git a/src/cli.cc b/src/cli.cc
index 2ba1040..a4badb5 100644
--- a/src/cli.cc
+++ b/src/cli.cc
@@ -12,6 +12,7 @@
 #include <config.h>
 #include <opustags.h>
 
+#include <errno.h>
 #include <getopt.h>
 #include <limits.h>
 #include <string.h>
diff --git a/src/ogg.cc b/src/ogg.cc
index 281ee8e..84080fa 100644
--- a/src/ogg.cc
+++ b/src/ogg.cc
@@ -10,6 +10,7 @@
 
 #include <opustags.h>
 
+#include <errno.h>
 #include <string.h>
 
 using namespace std::literals::string_literals;
diff --git a/src/system.cc b/src/system.cc
index e9d6b01..1f28789 100644
--- a/src/system.cc
+++ b/src/system.cc
@@ -11,7 +11,9 @@
 
 #include <opustags.h>
 
+#include <errno.h>
 #include <string.h>
+#include <unistd.h>
 
 ot::status ot::partial_file::open(const char* destination)
 {