diff --git a/Config.in b/Config.in
index 499233bc1..c5f8b3c0f 100644
--- a/Config.in
+++ b/Config.in
@@ -352,16 +352,25 @@ config DEBUG
 
 	  Most people should answer N.
 
-config DEBUG_PESSIMIZE
-	bool "Disable compiler optimizations."
+config WERROR
+	bool "Abort compilation on any warning"
 	default n
-	depends on DEBUG
 	help
-	  The compiler's optimization of source code can eliminate and reorder
-	  code, resulting in an executable that's hard to understand when
-	  stepping through it with a debugger.  This switches it off, resulting
-	  in a much bigger executable that more closely matches the source
-	  code.
+	  Selecting this will add -Werror to gcc command line.
+
+	  Most people should answer N.
+
+# Seems to be unused
+#config DEBUG_PESSIMIZE
+#	bool "Disable compiler optimizations."
+#	default n
+#	depends on DEBUG
+#	help
+#	  The compiler's optimization of source code can eliminate and reorder
+#	  code, resulting in an executable that's hard to understand when
+#	  stepping through it with a debugger.  This switches it off, resulting
+#	  in a much bigger executable that more closely matches the source
+#	  code.
 
 choice
 	prompt "Additional debugging library"
diff --git a/Makefile.flags b/Makefile.flags
index 8f6d0c9bd..cec73df8f 100644
--- a/Makefile.flags
+++ b/Makefile.flags
@@ -17,10 +17,15 @@ CPPFLAGS += \
 
 # flag checks are grouped together to speed the checks up a bit..
 CFLAGS += $(call cc-option,-Wall -Wshadow,)
+ifeq ($(CONFIG_WERROR),y)
+CFLAGS += $(call cc-option,-Werror,)
+endif
 CFLAGS += $(call cc-option,-Wundef -Wold-style-definition -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations,)
 CFLAGS += $(call cc-option,-Os -fno-builtin-strlen -finline-limit=0 -fomit-frame-pointer -ffunction-sections -fdata-sections,)
-CFLAGS += $(call cc-option,-static-libgcc -funsigned-char,)
-CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-loops=1,)
+# -fno-guess-branch-probability: prohibit pseudo-random guessing
+# of branch probabilities (hopefully makes bloatcheck more stable)
+CFLAGS += $(call cc-option,-funsigned-char -fno-guess-branch-probability -static-libgcc,)
+CFLAGS += $(call cc-option,-falign-functions=1 -falign-jumps=1 -falign-labels=1 -falign-loops=1,)
 
 # FIXME: These warnings are at least partially to be concerned about and should
 # be fixed..
diff --git a/scripts/defconfig b/scripts/defconfig
index ed9959985..a3e59c8aa 100644
--- a/scripts/defconfig
+++ b/scripts/defconfig
@@ -45,7 +45,7 @@ CONFIG_LFS=y
 # Debugging Options
 #
 # CONFIG_DEBUG is not set
-# CONFIG_DEBUG_PESSIMIZE is not set
+# CONFIG_WERROR is not set
 # CONFIG_NO_DEBUG_LIB is not set
 # CONFIG_DMALLOC is not set
 # CONFIG_EFENCE is not set