diff --git a/lib/curl_setup.h b/lib/curl_setup.h
index 9cda99ab88..c62a21fde7 100644
--- a/lib/curl_setup.h
+++ b/lib/curl_setup.h
@@ -1137,7 +1137,7 @@ typedef unsigned int curl_bit;
 #define SOCKEWOULDBLOCK   EWOULDBLOCK
 #endif
 
-#if !defined(USE_WINSOCK) && EAGAIN != SOCKEWOULDBLOCK
+#if !defined(USE_WINSOCK) && defined(EAGAIN) && EAGAIN != SOCKEWOULDBLOCK
 #define SOCK_EWOULDBLOCK_EAGAIN(e) ((e) == SOCKEWOULDBLOCK || (e) == EAGAIN)
 #else
 #define SOCK_EWOULDBLOCK_EAGAIN(e) ((e) == SOCKEWOULDBLOCK)
diff --git a/lib/vtls/rustls.c b/lib/vtls/rustls.c
index b598a174fb..f780179000 100644
--- a/lib/vtls/rustls.c
+++ b/lib/vtls/rustls.c
@@ -45,7 +45,7 @@
 #include "curlx/base64.h"
 #endif
 
-#if EAGAIN != SOCKEWOULDBLOCK
+#if defined(EAGAIN) && EAGAIN != SOCKEWOULDBLOCK
 #define RAW_EWOULDBLOCK_EAGAIN(e)  ((e) == EWOULDBLOCK || (e) == EAGAIN)
 #else
 #define RAW_EWOULDBLOCK_EAGAIN(e)  ((e) == EWOULDBLOCK)