diff --git a/TODO b/TODO
index bc7fb8b..e6e5b07 100644
--- a/TODO
+++ b/TODO
@@ -31,7 +31,6 @@ Bugs:
 - make libtcc fully reentrant (except for the compilation stage itself).
 - struct/union/enum definitions in nested scopes (see also Debian bug #770657)
 - __STDC_IEC_559__: float f(void) { static float x = 0.0 / 0.0; return x; }
-- preprocessor: #define Y(x) Z(x) {newline} #define X Y {newline} X(X(1))
 
 Portability:
 
@@ -94,7 +93,6 @@ Not critical:
 - handle void (__attribute__() *ptr)()
 - VLAs are implemented in a way that is not compatible with signals:
   http://lists.gnu.org/archive/html/tinycc-devel/2015-11/msg00018.html
-- output with -E should include spaces: #define n 0xe {newline} n+1
 
 Fixed (probably):
 
diff --git a/tccpp.c b/tccpp.c
index 94f0b5f..ad35687 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -3670,6 +3670,8 @@ ST_FUNC int tcc_preprocess(TCCState *s1)
 {
     BufferedFile **iptr;
     int token_seen, spcs, level;
+    const char *sp_chars = ""; /* insert space before any of these */
+    int prev_tok = 0;
 
     preprocess_init(s1);
     ch = file->buf_ptr[0];
@@ -3719,8 +3721,57 @@ ST_FUNC int tcc_preprocess(TCCState *s1)
             ++file->line_ref;
             token_seen = 0;
         }
-        if (s1->ppfp)
-            fputs(get_tok_str(tok, &tokc), s1->ppfp);
+        if (s1->ppfp) {
+            const char *t = get_tok_str(tok, &tokc);
+            if (strchr(sp_chars, t[0]) ||
+                ((tok >= TOK_IDENT || tok == TOK_PPNUM) &&
+                 (prev_tok >= TOK_IDENT || prev_tok == TOK_PPNUM)))
+                fputs(" ", s1->ppfp);
+            fputs(t, s1->ppfp);
+            prev_tok = tok;
+            switch (tok) {
+            case '+':
+                sp_chars = "+=";
+                break;
+            case '-':
+                sp_chars = "-=>";
+                break;
+            case '*':
+            case '/':
+            case '%':
+            case '^':
+            case '=':
+            case '!':
+            case TOK_A_SHL:
+            case TOK_A_SAR:
+                sp_chars = "=";
+                break;
+            case '&':
+                sp_chars = "&=";
+                break;
+            case '|':
+                sp_chars = "|=";
+                break;
+            case '<':
+                sp_chars = "<=";
+                break;
+            case '>':
+                sp_chars = ">=";
+                break;
+            case '.':
+                sp_chars = ".";
+                break;
+            case '#':
+                sp_chars = "#";
+                break;
+            case TOK_PPNUM:
+                sp_chars = "+-";
+                break;
+            default:
+                sp_chars = "";
+                break;
+            }
+        }
     }
 
     return 0;
diff --git a/tests/pp/15.c b/tests/pp/15.c
index 28a12bd..dc2b8d1 100644
--- a/tests/pp/15.c
+++ b/tests/pp/15.c
@@ -19,3 +19,8 @@ return A + B;
 #define B1 C1+2
 #define C1 A1+3
 return A1 + B1;
+
+#define i() x
+#define n() 1
+i()i()n()n()i()
+i()+i()-n()+n()-
diff --git a/tests/pp/15.expect b/tests/pp/15.expect
index 7ccee4a..d3d3dd5 100644
--- a/tests/pp/15.expect
+++ b/tests/pp/15.expect
@@ -1,6 +1,26 @@
+
+
 Z(1)
 Z(Z(1))
 Z(Z(Z(Z(Z(1)))))
+
+
+
 return A + B;
+
+
+
+
+
+
 return A+1 + B+1;
+
+
+
+
 return A1+3 +2 +1 + B1+1 +3 +2;
+
+
+
+x x 1 1 x
+x+x-1 +1 -