diff --git a/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf b/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
index 8d4988e8c6..a98be2cd95 100644
--- a/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
+++ b/CryptoPkg/Library/BaseCryptLib/BaseCryptLib.inf
@@ -101,5 +101,6 @@
 
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=incompatible-pointer-types
 
   XCODE:*_*_*_CC_FLAGS = -std=c99
diff --git a/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf b/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
index 3da8bd8480..7b07dd13d2 100644
--- a/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
+++ b/CryptoPkg/Library/BaseCryptLib/PeiCryptLib.inf
@@ -96,5 +96,6 @@
 
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=incompatible-pointer-types
 
   XCODE:*_*_*_CC_FLAGS = -std=c99
diff --git a/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf b/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
index 21a481eb77..d9e29ef660 100644
--- a/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
+++ b/CryptoPkg/Library/BaseCryptLib/RuntimeCryptLib.inf
@@ -107,5 +107,6 @@
 
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=incompatible-pointer-types
 
   XCODE:*_*_*_CC_FLAGS = -std=c99
diff --git a/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf b/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
index 7c187e21b3..b4faaf3f80 100644
--- a/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
+++ b/CryptoPkg/Library/BaseCryptLib/SmmCryptLib.inf
@@ -104,3 +104,4 @@
 
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=incompatible-pointer-types
diff --git a/CryptoPkg/Library/OpensslLib/OpensslLib.inf b/CryptoPkg/Library/OpensslLib/OpensslLib.inf
index 7432321fd4..b40d82783b 100644
--- a/CryptoPkg/Library/OpensslLib/OpensslLib.inf
+++ b/CryptoPkg/Library/OpensslLib/OpensslLib.inf
@@ -662,6 +662,7 @@
   GCC:*_*_AARCH64_CC_FLAGS = $(OPENSSL_FLAGS) -Wno-error=maybe-uninitialized -Wno-format -Wno-error=unused-but-set-variable
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized -Wno-error=incompatible-pointer-types -Wno-error=pointer-sign -Wno-error=implicit-function-declaration -Wno-error=ignored-pragma-optimize
 
   # suppress the following warnings in openssl so we don't break the build with warnings-as-errors:
   # 1295: Deprecated declaration <entity> - give arg types
diff --git a/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf b/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
index 8134b45eda..0a60196c8a 100644
--- a/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
+++ b/CryptoPkg/Library/OpensslLib/OpensslLibCrypto.inf
@@ -610,6 +610,7 @@
   GCC:*_*_AARCH64_CC_FLAGS = $(OPENSSL_FLAGS) -Wno-error=maybe-uninitialized -Wno-format -Wno-error=unused-but-set-variable
   GCC:*_CLANG35_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized
   GCC:*_CLANG38_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized
+  GCC:*_CLANG9_*_CC_FLAGS = -std=c99 -Wno-error=uninitialized -Wno-error=incompatible-pointer-types -Wno-error=pointer-sign -Wno-error=implicit-function-declaration -Wno-error=ignored-pragma-optimize
 
   # suppress the following warnings in openssl so we don't break the build with warnings-as-errors:
   # 1295: Deprecated declaration <entity> - give arg types