diff --git a/do-build b/do-build
index d5df0fc..041198a 100755
--- a/do-build
+++ b/do-build
@@ -298,9 +298,19 @@
     die "Configuration not supported. Use --force to try anyway."
   fi
 
-  if [ "$BUILD" != "$HOST" ] && [ -z "$SYSROOT" ] && [ -z "$force" ]
+  if [ -z "$SYSROOT" ] && [ -z "$force" ]
   then
-    die "Sysroot expected when host differs from build system. Use --force to try anyway."
+    if [ "$BUILD" != "$HOST" ]
+    then
+      die "Sysroot expected when host differs from build system. Use --force to try anyway."
+    fi
+
+    split_arch_os "$TARGET"
+    local target_os="$RESULT_OS"
+    if [ "$BUILD" != "$TARGET" ] && [ "$target_os" != "none" ]
+    then
+      die "Sysroot expected when target OS differs build OS. Use --force to try anyway."
+    fi
   fi
 
   mkdir -p "$OUT_DIR" || die "Unable to create directory $OUT_DIR"