diff --git a/simplecpp.cpp b/simplecpp.cpp
index babf611..928e123 100755
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -886,7 +886,7 @@ void simplecpp::TokenList::readfile(Stream &stream, const std::string &filename,
             }
 
             if (prefix.empty())
-                push_back(new Token(s, location)); // push string without newlines
+                push_back(new Token(s, location, isspace(stream.peekChar()))); // push string without newlines
             else
                 back()->setstr(prefix + s);
 
@@ -916,7 +916,7 @@ void simplecpp::TokenList::readfile(Stream &stream, const std::string &filename,
             }
         }
 
-        push_back(new Token(currentToken, location));
+        push_back(new Token(currentToken, location, isspace(stream.peekChar())));
 
         if (multiline)
             location.col += currentToken.size();
@@ -1546,9 +1546,9 @@ namespace simplecpp {
                 // Copy macro call to a new tokenlist with no linebreaks
                 const Token * const rawtok1 = rawtok;
                 TokenList rawtokens2(inputFiles);
-                rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location));
+                rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location, rawtok->whitespaceahead));
                 rawtok = rawtok->next;
-                rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location));
+                rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location, rawtok->whitespaceahead));
                 rawtok = rawtok->next;
                 int par = 1;
                 while (rawtok && par > 0) {
@@ -1558,7 +1558,7 @@ namespace simplecpp {
                         --par;
                     else if (rawtok->op == '#' && !sameline(rawtok->previous, rawtok))
                         throw Error(rawtok->location, "it is invalid to use a preprocessor directive as macro parameter");
-                    rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location));
+                    rawtokens2.push_back(new Token(rawtok->str(), rawtok1->location, rawtok->whitespaceahead));
                     rawtok = rawtok->next;
                 }
                 if (expand(&output2, rawtok1->location, rawtokens2.cfront(), macros, expandedmacros))
@@ -2128,6 +2128,8 @@ namespace simplecpp {
                     partok = partok->next;
                 }
             }
+            if (tok->whitespaceahead && output->back())
+                output->back()->whitespaceahead = true;
             return true;
         }
 
@@ -2146,8 +2148,12 @@ namespace simplecpp {
             tok = expandToken(&tokenListHash, loc, tok->next, macros2, expandedmacros, parametertokens);
             std::ostringstream ostr;
             ostr << '\"';
-            for (const Token *hashtok = tokenListHash.cfront(); hashtok; hashtok = hashtok->next)
+            for (const Token *hashtok = tokenListHash.cfront(), *next; hashtok; hashtok = next) {
+                next = hashtok->next;
                 ostr << hashtok->str();
+                if (next && hashtok->whitespaceahead)
+                    ostr << ' ';
+            }
             ostr << '\"';
             output->push_back(newMacroToken(escapeString(ostr.str()), loc, isReplaced(expandedmacros)));
             return tok;
diff --git a/simplecpp.h b/simplecpp.h
index 88a1401..672f29a 100755
--- a/simplecpp.h
+++ b/simplecpp.h
@@ -94,13 +94,13 @@ namespace simplecpp {
      */
     class SIMPLECPP_LIB Token {
     public:
-        Token(const TokenString &s, const Location &loc) :
-            location(loc), previous(nullptr), next(nullptr), string(s) {
+        Token(const TokenString &s, const Location &loc, bool wsahead = false) :
+            whitespaceahead(wsahead), location(loc), previous(nullptr), next(nullptr), string(s) {
             flags();
         }
 
         Token(const Token &tok) :
-            macro(tok.macro), op(tok.op), comment(tok.comment), name(tok.name), number(tok.number), location(tok.location), previous(nullptr), next(nullptr), string(tok.string), mExpandedFrom(tok.mExpandedFrom) {
+            macro(tok.macro), op(tok.op), comment(tok.comment), name(tok.name), number(tok.number), whitespaceahead(tok.whitespaceahead), location(tok.location), previous(nullptr), next(nullptr), string(tok.string), mExpandedFrom(tok.mExpandedFrom) {
         }
 
         void flags() {
@@ -132,6 +132,7 @@ namespace simplecpp {
         bool comment;
         bool name;
         bool number;
+        bool whitespaceahead;
         Location location;
         Token *previous;
         Token *next;
@@ -153,6 +154,8 @@ namespace simplecpp {
         void setExpandedFrom(const Token *tok, const Macro* m) {
             mExpandedFrom = tok->mExpandedFrom;
             mExpandedFrom.insert(m);
+            if (tok->whitespaceahead)
+                whitespaceahead = true;
         }
         bool isExpandedFrom(const Macro* m) const {
             return mExpandedFrom.find(m) != mExpandedFrom.end();
diff --git a/test.cpp b/test.cpp
index e6210ec..1e42fad 100644
--- a/test.cpp
+++ b/test.cpp
@@ -47,7 +47,7 @@ static int assertEquals(const std::string &expected, const std::string &actual,
     return (expected == actual);
 }
 
-static int assertEquals(const unsigned int &expected, const unsigned int &actual, int line)
+static int assertEquals(const long long &expected, const long long &actual, int line)
 {
     return assertEquals(std::to_string(expected), std::to_string(actual), line);
 }
@@ -1038,6 +1038,12 @@ static void hash()
                   preprocess("#define bar(x) x % 2\n"
                              "#define foo(x) printf(#x \"\\n\")\n"
                              "foo(bar(3));"));
+
+    ASSERT_EQUALS("\n\n\n\"Y Y\"",
+                  preprocess("#define X(x,y)    x y\n"
+                             "#define STR_(x)   #x\n"
+                             "#define STR(x)    STR_(x)\n"
+                             "STR(X(Y,Y))"));
 }
 
 static void hashhash1()   // #4703