diff --git a/configure b/configure
index c573a777fc..c9cb740130 100755
--- a/configure
+++ b/configure
@@ -537,8 +537,24 @@ elif check_define __sun__ ; then
   targetos='SunOS'
 elif check_define __HAIKU__ ; then
   targetos='Haiku'
+elif check_define __FreeBSD__ ; then
+  targetos='FreeBSD'
+elif check_define __FreeBSD_kernel__ && check_define __GLIBC__; then
+  targetos='GNU/kFreeBSD'
+elif check_define __DragonFly__ ; then
+  targetos='DragonFly'
+elif check_define __NetBSD__; then
+  targetos='NetBSD'
+elif check_define __APPLE__; then
+  targetos='Darwin'
+elif check_define _AIX; then
+  targetos='AIX'
 else
-  targetos=$(uname -s)
+  # This is a fatal error, but don't report it yet, because we
+  # might be going to just print the --help text, or it might
+  # be the result of a missing compiler.
+  targetos='bogus'
+  bogus_os='yes'
 fi
 
 # Some host OSes need non-standard checks for which CPU to use.
@@ -782,12 +798,6 @@ Linux)
   QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$(pwd)/linux-headers $QEMU_INCLUDES"
   supported_os="yes"
 ;;
-*)
-  # This is a fatal error, but don't report it yet, because we
-  # might be going to just print the --help text, or it might
-  # be the result of a missing compiler.
-  bogus_os="yes"
-;;
 esac
 
 if [ "$bsd" = "yes" ] ; then
@@ -1582,7 +1592,7 @@ if test "$bogus_os" = "yes"; then
     # the compiler works (so the results of the check_defines we used
     # to identify the OS are reliable), if we didn't recognize the
     # host OS we should stop now.
-    error_exit "Unrecognized host OS $targetos"
+    error_exit "Unrecognized host OS (uname -s reports '$(uname -s)')"
 fi
 
 gcc_flags="-Wold-style-declaration -Wold-style-definition -Wtype-limits"