diff --git a/boards/sim/sim/sim/configs/cxxtest/Make.defs b/boards/sim/sim/sim/configs/cxxtest/Make.defs
index 7146e1ad712..ef5fcad607b 100644
--- a/boards/sim/sim/sim/configs/cxxtest/Make.defs
+++ b/boards/sim/sim/sim/configs/cxxtest/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
diff --git a/boards/sim/sim/sim/configs/nsh2/Make.defs b/boards/sim/sim/sim/configs/nsh2/Make.defs
index e329be3f6d1..1fefa4daeb7 100644
--- a/boards/sim/sim/sim/configs/nsh2/Make.defs
+++ b/boards/sim/sim/sim/configs/nsh2/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS			= ${shell uname -o 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION	= -g
diff --git a/boards/sim/sim/sim/scripts/Make.defs b/boards/sim/sim/sim/scripts/Make.defs
index 94d53bb8726..45583504a29 100644
--- a/boards/sim/sim/sim/scripts/Make.defs
+++ b/boards/sim/sim/sim/scripts/Make.defs
@@ -37,7 +37,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_WINDOWS_MSYS),y)
   DIRLINK = $(TOPDIR)/tools/copydir.sh
diff --git a/boards/x86/qemu/qemu-i486/scripts/Make.defs b/boards/x86/qemu/qemu-i486/scripts/Make.defs
index e153be8967e..df4c8799b7f 100644
--- a/boards/x86/qemu/qemu-i486/scripts/Make.defs
+++ b/boards/x86/qemu/qemu-i486/scripts/Make.defs
@@ -36,7 +36,7 @@
 include ${TOPDIR}/.config
 include ${TOPDIR}/tools/Config.mk
 
-HOSTOS = ${shell uname -o 2>/dev/null || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
 
 ifeq ($(CONFIG_DEBUG_SYMBOLS),y)
   ARCHOPTIMIZATION = -g
diff --git a/tools/Makefile.host b/tools/Makefile.host
index 07ebe9ea3b5..71e87e59c6d 100644
--- a/tools/Makefile.host
+++ b/tools/Makefile.host
@@ -43,7 +43,7 @@ include ${TOPDIR}/tools/Config.mk
 # Define HOSTCC on the make command line if it differs from these defaults
 # Define HOSTCFLAGS with -g on the make command line to build debug versions
 
-HOSTOS = ${shell uname -o || echo "Other"}
+HOSTOS = ${shell uname -o 2>/dev/null || uname -s 2>/dev/null || echo "Other"}
 
 ifeq ($(HOSTOS),MinGW)