diff --git a/rpmio/macro.c b/rpmio/macro.c
index 7ef216109..5e4d1b390 100644
--- a/rpmio/macro.c
+++ b/rpmio/macro.c
@@ -1012,6 +1012,93 @@ doFoo(MacroBuf mb, int negate, const char * f, size_t fn,
     free(buf);
 }
 
+/**
+ * Parse for flags before macro name, such as in %{?!name:subst}.
+ * @param s		macro flags start
+ * @param negate	flipped by each '!' flag
+ * @param chkexist	increased by each '?' flag
+ * @return		macro flags end
+ */
+static const char *
+parseMacroFlags(const char *s, int *negate, int *chkexist)
+{
+    while (1) {
+	switch (*s) {
+	case '!':
+	    *negate = !*negate;
+	    s++;
+	    break;
+	case '?':
+	    (*chkexist)++;
+	    s++;
+	    break;
+	default:
+	    return s;
+	}
+    }
+    /* not reached */
+    return s;
+}
+
+/**
+ * Parse for valid macro name (during expansion).
+ * @param s		macro name start
+ * @return		macro name end, NULL on error
+ */
+static const char *
+parseMacroName(const char *s)
+{
+    /* alnum identifiers */
+    if (risalpha(*s) || *s == '_') {
+	const char *se = s + 1;
+	while (risalnum(*se) || *se == '_')
+	    se++;
+	switch (se - s) {
+	case 1:
+	    /* recheck for [SPF] */
+	    break;
+	case 2:
+	    return NULL;
+	default:
+	    return se;
+	}
+    }
+    /* simple special names */
+    switch (*s) {
+    case '0':
+    case '#':
+    case 'S':
+    case 'P':
+    case 'F':
+	s++;
+	return s;
+    case '*':
+	s++;
+	if (*s == '*')
+	    s++;
+	return s;
+    /* option names */
+    case '-':
+	s++;
+	if (risalnum(*s))
+	    s++;
+	else
+	    return NULL;
+	if (*s == '*')
+	    s++;
+	return s;
+    }
+    /* argument names */
+    if (risdigit(*s)) {
+	s++;
+	while (risdigit(*s))
+	    s++;
+	return s;
+    }
+    /* invalid macro name */
+    return NULL;
+}
+
 /**
  * The main macro recursion loop.
  * @param mb		macro expansion state
@@ -1085,34 +1172,14 @@ expandMacro(MacroBuf mb, const char *src, size_t slen)
 	chkexist = 0;
 	switch ((c = *s)) {
 	default:		/* %name substitution */
-		while (strchr("!?", *s) != NULL) {
-			switch(*s++) {
-			case '!':
-				negate = ((negate + 1) % 2);
-				break;
-			case '?':
-				chkexist++;
-				break;
-			}
+		f = parseMacroFlags(s, &negate, &chkexist);
+		fe = parseMacroName(f);
+		/* no valid name? assume as-is substitution */
+		if (fe == NULL) {
+			mbAppend(mb, '%');
+			continue;
 		}
-		f = se = s;
-		if (*se == '-')
-			se++;
-		while((c = *se) && (risalnum(c) || c == '_'))
-			se++;
-		/* Recognize non-alnum macros too */
-		switch (*se) {
-		case '*':
-			se++;
-			if (*se == '*') se++;
-			break;
-		case '#':
-			se++;
-			break;
-		default:
-			break;
-		}
-		fe = se;
+		se = fe;
 		/* For "%name " macros ... */
 		if ((c = *fe) && isblank(c))
 			if ((lastc = strchr(fe,'\n')) == NULL)
@@ -1142,48 +1209,39 @@ expandMacro(MacroBuf mb, const char *src, size_t slen)
 			rc = 1;
 			continue;
 		}
-		f = s+1;/* skip { */
+		f = parseMacroFlags(s + 1 /* skip { */, &negate, &chkexist);
+		fe = parseMacroName(f);
 		se++;	/* skip } */
-		while (strchr("!?", *f) != NULL) {
-			switch(*f++) {
-			case '!':
-				negate = ((negate + 1) % 2);
-				break;
-			case '?':
-				chkexist++;
-				break;
-			}
+		/* no valid name? syntax error */
+		if (fe == NULL) {
+			rpmlog(RPMLOG_ERR,
+				_("Invalid macro name: %%%.*s\n"), (int)(se - s), s);
+			rc = 1;
+			continue;
 		}
-		for (fe = f; (c = *fe) && !strchr(" :}", c);)
-			fe++;
-		switch (c) {
+		switch (*fe) {
 		case ':':
 			g = fe + 1;
 			ge = se - 1;
 			break;
 		case ' ':
+		case '\t':
 			lastc = se-1;
 			break;
-		default:
+		case '}':
 			break;
+		default:
+			rpmlog(RPMLOG_ERR,
+				_("Invalid macro syntax: %%%.*s\n"), (int)(se - s), s);
+			rc = 1;
+			continue;
 		}
 		break;
 	}
 
-	/* XXX Everything below expects fe > f */
+	assert(fe > f);
 	fn = (fe - f);
 	gn = (ge - g);
-	if ((fe - f) <= 0) {
-/* XXX Process % in unknown context */
-		c = '%';	/* XXX only need to save % */
-		mbAppend(mb, c);
-#if 0
-		rpmlog(RPMLOG_ERR,
-			_("A %% is followed by an unparseable macro\n"));
-#endif
-		s = se;
-		continue;
-	}
 
 	if (mb->macro_trace)
 		printMacro(mb, s, se);