diff --git a/bitbake/lib/bb/data.py b/bitbake/lib/bb/data.py
index e3ffefeb36..5b7a092a21 100644
--- a/bitbake/lib/bb/data.py
+++ b/bitbake/lib/bb/data.py
@@ -291,6 +291,8 @@ def build_dependencies(key, keys, shelldeps, vardepvals, d):
             if d.getVarFlag(key, "python"):
                 parsedvar = d.expandWithRefs(value, key)
                 parser = bb.codeparser.PythonParser(key, logger)
+                if parsedvar.value and "\t" in parsedvar.value:
+                    logger.warn("Variable %s contains tabs, please remove these (%s)" % (key, d.getVar("FILE", True)))
                 parser.parse_python(parsedvar.value)
                 deps = deps | parser.references
             else:
diff --git a/bitbake/lib/bb/parse/ast.py b/bitbake/lib/bb/parse/ast.py
index eae840fa8d..86f94636b9 100644
--- a/bitbake/lib/bb/parse/ast.py
+++ b/bitbake/lib/bb/parse/ast.py
@@ -212,9 +212,9 @@ class ExportFuncsNode(AstNode):
                         data.setVarFlag(calledvar, flag, data.getVarFlag(var, flag))
 
                 if data.getVarFlag(calledvar, "python"):
-                    data.setVar(var, "\tbb.build.exec_func('" + calledvar + "', d)\n")
+                    data.setVar(var, "    bb.build.exec_func('" + calledvar + "', d)\n")
                 else:
-                    data.setVar(var, "\t" + calledvar + "\n")
+                    data.setVar(var, "    " + calledvar + "\n")
                 data.setVarFlag(var, 'export_func', '1')
 
 class AddTaskNode(AstNode):