diff --git a/make/lib/Awt2dLibraries.gmk b/make/lib/Awt2dLibraries.gmk
index e5768360b239f887b969df44bf303de6398a00d8..302c08933b7ac8bf64606aea6ba4da7f4beaddf5 100644
--- a/make/lib/Awt2dLibraries.gmk
+++ b/make/lib/Awt2dLibraries.gmk
@@ -371,6 +371,13 @@ else
   BUILD_LIBLCMS_INCLUDE_FILES :=
 endif
 
+ifeq ($(TOOLCHAIN_TYPE), clang)
+ ifeq ($(TOOLCHAIN_VERSION), 10.1)
+   # Work around an optimizer bug seen with Xcode 10.1, but fixed by 10.3
+   BUILD_LIBLCMS_cmsopt.c_CFLAGS := -O0
+ endif
+endif
+
 $(eval $(call SetupJdkLibrary, BUILD_LIBLCMS, \
     NAME := lcms, \
     INCLUDE_FILES := $(BUILD_LIBLCMS_INCLUDE_FILES), \
diff --git a/src/java.desktop/share/native/liblcms/cmsps2.c b/src/java.desktop/share/native/liblcms/cmsps2.c
index a3c7b49dbff25792c781a330aa755b260ec7a368..3f373d808f2fa54be0b99188b3166ac7f0712e0e 100644
--- a/src/java.desktop/share/native/liblcms/cmsps2.c
+++ b/src/java.desktop/share/native/liblcms/cmsps2.c
@@ -1443,7 +1443,7 @@ int WriteNamedColorCRD(cmsIOHANDLER* m, cmsHPROFILE hNamedColor, cmsUInt32Number
     cmsUInt32Number i, nColors, nColorant;
     cmsUInt32Number OutputFormat;
     char ColorName[cmsMAX_PATH];
-    char Colorant[128];
+    char Colorant[512];
     cmsNAMEDCOLORLIST* NamedColorList;