diff --git a/simplecpp.cpp b/simplecpp.cpp
index 5bd5cac..67e59ab 100755
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -1002,7 +1002,7 @@ void simplecpp::TokenList::combineOperators()
                 continue;
             }
             // float literals..
-            if (tok->previous && tok->previous->number && sameline(tok->previous, tok)) {
+            if (tok->previous && tok->previous->number && sameline(tok->previous, tok) && tok->previous->str().find_first_of("._") == std::string::npos) {
                 tok->setstr(tok->previous->str() + '.');
                 deleteToken(tok->previous);
                 if (sameline(tok, tok->next) && (isFloatSuffix(tok->next) || (tok->next && tok->next->startsWithOneOf("AaBbCcDdEeFfPp")))) {
diff --git a/test.cpp b/test.cpp
index d8e359e..5b88978 100644
--- a/test.cpp
+++ b/test.cpp
@@ -390,6 +390,8 @@ static void combineOperators_floatliteral()
     ASSERT_EQUALS("0x1p+3f", preprocess("0x1p+3f"));
     ASSERT_EQUALS("0x1p+3L", preprocess("0x1p+3L"));
     ASSERT_EQUALS("1p + 3", preprocess("1p+3"));
+    ASSERT_EQUALS("1.0_a . b", preprocess("1.0_a.b"));
+    ASSERT_EQUALS("1_a . b", preprocess("1_a.b"));
 }
 
 static void combineOperators_increment()