diff --git a/io.cpp b/io.cpp
index 7bc836ec..14b02716 100644
--- a/io.cpp
+++ b/io.cpp
@@ -6,7 +6,6 @@
 #include <cstdio>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
 
@@ -68,6 +67,9 @@ fd_ref::operator int (void) const
     { return fd; }
 
 
+#if defined(HAVE_MMAP)
+#include <sys/mman.h>
+
 //----------------------------------------------------------------------------
 mapped_file::mapped_file (const char *_path):
     m_fd (open (_path, O_RDONLY))
@@ -119,6 +121,6 @@ mapped_file::data (void) const {
 
     return m_data;
 }
-
+#endif
 
 
diff --git a/io.hpp b/io.hpp
index c7931eb5..65e5ed11 100644
--- a/io.hpp
+++ b/io.hpp
@@ -52,6 +52,7 @@ struct fd_ref {
 };
 
 
+#if defined(HAVE_MMAP)
 /// Wraps a mechanism to map a file into memory. Read only.
 class mapped_file {
     protected:
@@ -74,6 +75,7 @@ class mapped_file {
         const uint8_t* data (void) const;
         size_t         size (void) const;
 };
+#endif
 
 
 #endif