diff --git a/common.mk b/common.mk
index 6baac2b..5a6a127 100644
--- a/common.mk
+++ b/common.mk
@@ -160,6 +160,7 @@ CFLAGS += -D DEBUG
 #STRIPFLAGS += -Wl,-s
 
 # OS specific flags
+OS := $(shell uname)
 ifeq "$(OS)" "DragonFly"
 	CFLAGS += -I/usr/pkg/include
 	LDFLAGS += -L/usr/pkg/lib
diff --git a/libowlps-resultreader/Makefile b/libowlps-resultreader/Makefile
index 1003c5c..4617d81 100644
--- a/libowlps-resultreader/Makefile
+++ b/libowlps-resultreader/Makefile
@@ -9,7 +9,6 @@ EXAMPLE = owlps-resultreader-udp
 ## Additional libraries ##
 
 LDFLAGS += -lowlps
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif
diff --git a/owlps-aggregator/Makefile b/owlps-aggregator/Makefile
index 318c83d..69a4500 100644
--- a/owlps-aggregator/Makefile
+++ b/owlps-aggregator/Makefile
@@ -7,7 +7,6 @@ HEADER = owlps-aggregator.h
 ## Additional libraries ##
 
 LDFLAGS += -pthread -lconfuse -lowlps
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif
diff --git a/owlps-client/Makefile b/owlps-client/Makefile
index 723fa16..03d578a 100644
--- a/owlps-client/Makefile
+++ b/owlps-client/Makefile
@@ -15,7 +15,6 @@ STATIC_LDFLAGS += $(LIBOWLPS_DIR)/libowlps.a $(LIBOWLPSCLIENT_DIR)/libowlps-clie
 SEMISTATIC_LDFLAGS += $(STATIC_LDFLAGS)
 DYNAMIC_LDFLAGS += -lowlps -lowlps-client
 
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif
diff --git a/owlps-listener/Makefile b/owlps-listener/Makefile
index 46a5746..bfe1a0c 100644
--- a/owlps-listener/Makefile
+++ b/owlps-listener/Makefile
@@ -22,7 +22,6 @@ STATIC_LDFLAGS += $(LIBOWLPS_DIR)/libowlps.a $(LIBOWLPSCLIENT_DIR)/libowlps-clie
 SEMISTATIC_LDFLAGS += $(STATIC_LDFLAGS)
 DYNAMIC_LDFLAGS += -lowlps -lowlps-client
 
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif
diff --git a/owlps-positioner/Makefile b/owlps-positioner/Makefile
index c7cd95c..01f34a2 100644
--- a/owlps-positioner/Makefile
+++ b/owlps-positioner/Makefile
@@ -18,7 +18,6 @@ TESTSCXXFLAGS = -I$(TESTS_DIR) -I$(SRC_DIR) -I.
 ## Additional libraries ##
 
 LDFLAGS += -lstdc++ -lm -lboost_program_options -pthread -lowlps
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif
diff --git a/owlps-udp-to-http/Makefile b/owlps-udp-to-http/Makefile
index 2251f59..a119b53 100644
--- a/owlps-udp-to-http/Makefile
+++ b/owlps-udp-to-http/Makefile
@@ -6,7 +6,6 @@ TARGET = owlps-udp-to-http
 ## Additional libraries ##
 
 LDFLAGS += -pthread -lowlps -lowlps-resultreader
-OS := $(shell uname)
 ifeq "$(OS)" "Linux"
 	LDFLAGS += -lrt
 endif