diff --git a/drivers/builtin_openssl2/SCsub b/drivers/builtin_openssl2/SCsub
index a51b0a3ed6a..395dd21eef4 100644
--- a/drivers/builtin_openssl2/SCsub
+++ b/drivers/builtin_openssl2/SCsub
@@ -650,8 +650,10 @@ env_ssl.Append(CPPPATH=["#drivers/builtin_openssl2/crypto/asn1"])
 env_ssl.Append(CPPPATH=["#drivers/builtin_openssl2/crypto/modes"])
 #env_ssl.Append(CPPPATH=["#drivers/builtin_openssl2/crypto/store"])
 env_ssl.Append(CPPFLAGS=["-DOPENSSL_NO_ASM","-DOPENSSL_THREADS","-DL_ENDIAN"])
-env_ssl.Append(CFLAGS=["-Wno-error=implicit-function-declaration"]);
+
+# Workaround for compilation error with GCC/Clang when -Werror is too greedy (GH-4517)
+import os
+if not (os.name=="nt" and os.getenv("VSINSTALLDIR")!=None): # not Windows and not MSVC
+	env_ssl.Append(CFLAGS=["-Wno-error=implicit-function-declaration"])
 
 env_ssl.add_source_files(env.drivers_sources,openssl_sources)
-
-