diff --git Source/WTF/wtf/RandomDevice.cpp Source/WTF/wtf/RandomDevice.cpp
index 61d6057..90fa30c 100644
--- Source/WTF/wtf/RandomDevice.cpp
+++ Source/WTF/wtf/RandomDevice.cpp
@@ -30,24 +30,12 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-#if !OS(DARWIN) && OS(UNIX)
 #include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
-#endif
-
-#if OS(WINDOWS)
-#include <windows.h>
-#include <wincrypt.h> // windows.h must be included before wincrypt.h.
-#endif
-
-#if OS(DARWIN)
-#include "CommonCryptoSPI.h"
-#endif
 
 namespace WTF {
 
-#if !OS(DARWIN) && OS(UNIX)
 NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToOpenURandom()
 {
     CRASH();
@@ -57,9 +45,7 @@ NEVER_INLINE NO_RETURN_DUE_TO_CRASH static void crashUnableToReadFromURandom()
 {
     CRASH();
 }
-#endif
 
-#if !OS(DARWIN) && !OS(WINDOWS)
 RandomDevice::RandomDevice()
 {
     int ret = 0;
@@ -70,22 +56,16 @@ RandomDevice::RandomDevice()
     if (m_fd < 0)
         crashUnableToOpenURandom(); // We need /dev/urandom for this API to work...
 }
-#endif
 
-#if !OS(DARWIN) && !OS(WINDOWS)
 RandomDevice::~RandomDevice()
 {
     close(m_fd);
 }
-#endif
 
 // FIXME: Make this call fast by creating the pool in RandomDevice.
 // https://bugs.webkit.org/show_bug.cgi?id=170190
 void RandomDevice::cryptographicallyRandomValues(unsigned char* buffer, size_t length)
 {
-#if OS(DARWIN)
-    RELEASE_ASSERT(!CCRandomCopyBytes(kCCRandomDefault, buffer, length));
-#elif OS(UNIX)
     ssize_t amountRead = 0;
     while (static_cast<size_t>(amountRead) < length) {
         ssize_t currentRead = read(m_fd, buffer + amountRead, length - amountRead);
@@ -97,20 +77,6 @@ void RandomDevice::cryptographicallyRandomValues(unsigned char* buffer, size_t l
         } else
             amountRead += currentRead;
     }
-#elif OS(WINDOWS)
-    // FIXME: We cannot ensure that Cryptographic Service Provider context and CryptGenRandom are safe across threads.
-    // If it is safe, we can acquire context per RandomDevice.
-    HCRYPTPROV hCryptProv = 0;
-    if (!CryptAcquireContext(&hCryptProv, 0, MS_DEF_PROV, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
-        CRASH();
-    if (!CryptGenRandom(hCryptProv, length, buffer))
-        CRASH();
-    CryptReleaseContext(hCryptProv, 0);
-#else
-#error "This configuration doesn't have a strong source of randomness."
-// WARNING: When adding new sources of OS randomness, the randomness must
-//          be of cryptographic quality!
-#endif
 }
 
 }
diff --git Source/WTF/wtf/RandomDevice.h Source/WTF/wtf/RandomDevice.h
index 86636c9..410ccd0 100644
--- Source/WTF/wtf/RandomDevice.h
+++ Source/WTF/wtf/RandomDevice.h
@@ -34,12 +34,8 @@ namespace WTF {
 class RandomDevice {
     WTF_MAKE_NONCOPYABLE(RandomDevice);
 public:
-#if OS(DARWIN) || OS(WINDOWS)
-    RandomDevice() = default;
-#else
     RandomDevice();
     ~RandomDevice();
-#endif
 
     // This function attempts to fill buffer with randomness from the operating
     // system. Rather than calling this function directly, consider calling
@@ -47,14 +43,7 @@ public:
     void cryptographicallyRandomValues(unsigned char* buffer, size_t length);
 
 private:
-#if OS(DARWIN) || OS(WINDOWS)
-#elif OS(UNIX)
     int m_fd { -1 };
-#else
-#error "This configuration doesn't have a strong source of randomness."
-// WARNING: When adding new sources of OS randomness, the randomness must
-//          be of cryptographic quality!
-#endif
 };
 
 }