diff --git a/src/compat.h b/src/compat.h
index d4dc3ba99..d9253c867 100644
--- a/src/compat.h
+++ b/src/compat.h
@@ -75,6 +75,12 @@ typedef u_int SOCKET;
 #define MAX_PATH            1024
 #endif
 
+// ssize_t is POSIX, and not present when using MSVC.
+#ifdef _MSC_VER
+#include <BaseTsd.h>
+typedef SSIZE_T ssize_t;
+#endif
+
 // As Solaris does not have the MSG_NOSIGNAL flag for send(2) syscall, it is defined as 0
 #if !defined(HAVE_MSG_NOSIGNAL) && !defined(MSG_NOSIGNAL)
 #define MSG_NOSIGNAL 0
diff --git a/src/random.h b/src/random.h
index b35cf51a1..6503d8359 100644
--- a/src/random.h
+++ b/src/random.h
@@ -121,7 +121,7 @@ public:
  * sure that the underlying OS APIs for all platforms support the number.
  * (many cap out at 256 bytes).
  */
-static const ssize_t NUM_OS_RANDOM_BYTES = 32;
+static const int NUM_OS_RANDOM_BYTES = 32;
 
 /** Get 32 bytes of system entropy. Do not use this in application code: use
  * GetStrongRandBytes instead.