diff --git a/src/tgba/acc.cc b/src/tgba/acc.cc
index 2c02a83c4..eded9e16c 100644
--- a/src/tgba/acc.cc
+++ b/src/tgba/acc.cc
@@ -88,6 +88,9 @@ namespace spot
 	      }
 	    else
 	      {
+		if (!top)
+		  // Avoid extra parentheses if there is only one set
+		  top = code[pos - 1].mark.count() == 1;
 		unsigned level = 0;
 		const char* and_ = "";
 		if (!top)
@@ -118,6 +121,9 @@ namespace spot
 	      }
 	    else
 	      {
+		if (!top)
+		  // Avoid extra parentheses if there is only one set
+		  top = code[pos - 1].mark.count() == 1;
 		unsigned level = 0;
 		const char* or_ = "";
 		if (!top)
diff --git a/src/tgbatest/acc.test b/src/tgbatest/acc.test
index bab703707..c0fb7b2a3 100755
--- a/src/tgbatest/acc.test
+++ b/src/tgbatest/acc.test
@@ -60,10 +60,10 @@ stripping
 #1: {4}
 #1: {2}
 2 Inf(0)&Inf(1)&Inf(3)
-5 (Fin(2)) | (Inf(0)&Inf(1)&Inf(3))
-7 (Fin(0)) | (Fin(2)) | (Inf(0)&Inf(1)&Inf(3))
-7 (Fin(0)) | (Fin(2)) | (Inf(0)&Inf(1)&Inf(3))
-7 (Fin(0)) | (Fin(2)) | (Inf(0)&Inf(1)&Inf(3))
+5 Fin(2) | (Inf(0)&Inf(1)&Inf(3))
+7 Fin(0) | Fin(2) | (Inf(0)&Inf(1)&Inf(3))
+7 Fin(0) | Fin(2) | (Inf(0)&Inf(1)&Inf(3))
+7 Fin(0) | Fin(2) | (Inf(0)&Inf(1)&Inf(3))
 2 f
 EOF