diff --git a/src/arch/arm64/Makefile.inc b/src/arch/arm64/Makefile.inc
index 1aee6b83f7..a8742f2e13 100644
--- a/src/arch/arm64/Makefile.inc
+++ b/src/arch/arm64/Makefile.inc
@@ -184,10 +184,7 @@ BL31_MAKEARGS += BUILD_PLAT="$(BL31_BUILD)"
 BL31_MAKEARGS += IS_ANYTHING_TO_BUILD=1
 
 # Set a consistent build timestamp: the same coreboot has
-# The \# \" complications exist to satisfy both gnu make's parser and editors
-# with non-semantic quote-handling (that would assume that this line starts a
-# multi line string.
-BL31_MAKEARGS += BUILD_MESSAGE_TIMESTAMP='"$(shell grep "\#define COREBOOT_BUILD\>" $(obj)/build.h |cut -d\" -f2 \# \")"'
+BL31_MAKEARGS += BUILD_MESSAGE_TIMESTAMP='"$(shell sed -n 's/^.define COREBOOT_BUILD\>.*"\(.*\)".*/\1/p' $(obj)/build.h)"'
 
 BL31_CFLAGS := -fno-pic -fno-stack-protector -Wno-deprecated-declarations -Wno-unused-function
 BL31_LDFLAGS := --emit-relocs