diff --git a/src/libregexis024sol/sol_misc_base.cpp b/src/libregexis024sol/sol_misc_base.cpp
index b0e85c4..54f91dc 100644
--- a/src/libregexis024sol/sol_misc_base.cpp
+++ b/src/libregexis024sol/sol_misc_base.cpp
@@ -36,7 +36,7 @@ namespace regexis024 {
     }
 
     bool is_REGEX024_nameConstituent(int32_t ch) {
-        return ('0' <= ch && ch <= '9') || ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z');
+        return ('0' <= ch && ch <= '9') || ('a' <= ch && ch <= 'z') || ('A' <= ch && ch <= 'Z') || ch == '_';
     }
 
     std::string tryRead_REGEX024_name(REGEX_IS024_MeaningContext &ctx) {