diff --git a/src/plugins/cpptools/cpptoolsreuse.cpp b/src/plugins/cpptools/cpptoolsreuse.cpp
index bb2d52c401e..7f1abe5a205 100644
--- a/src/plugins/cpptools/cpptoolsreuse.cpp
+++ b/src/plugins/cpptools/cpptoolsreuse.cpp
@@ -117,7 +117,7 @@ bool isOwnershipRAIIType(CPlusPlus::Symbol *symbol, const LookupContext &context
 
 bool isValidAsciiIdentifierChar(const QChar &ch)
 {
-    return ch.isLetterOrNumber() || ch == QLatin1Char(' ');
+    return ch.isLetterOrNumber() || ch == QLatin1Char('_');
 }
 
 bool isValidFirstIdentifierChar(const QChar &ch)