Index: uspace/Makefile.common
===================================================================
--- uspace/Makefile.common	(revision 90c340fbb6e99eb264eb9d03d1501acb54b1f097)
+++ uspace/Makefile.common	(revision 37e8c4a1c218e8d69819bd4f761fa694e0884dad)
@@ -158,5 +158,5 @@
 
 AFLAGS =
-LFLAGS = --fatal-warnings
+LFLAGS = --fatal-warnings --warn-common
 
 # FIXME: This condition is a workaround for issues #692 and #693.
@@ -234,5 +234,5 @@
 COMMON_CFLAGS = $(INCLUDES_FLAGS) -O$(OPTIMIZATION) -imacros $(CONFIG_HEADER) \
 	-ffreestanding -fno-builtin -nostdlib -nostdinc -fexec-charset=UTF-8 \
-	-finput-charset=UTF-8 -D__$(ENDIANESS)__
+	-finput-charset=UTF-8 -D__$(ENDIANESS)__ -fno-common
 
 GCC_CFLAGS = -ffunction-sections -Wall -Wextra -Wno-clobbered \