diff --git a/src/frontend/parse-bison.y b/src/frontend/parse-bison.y
index 2cb2b5c6a..c99466761 100644
--- a/src/frontend/parse-bison.y
+++ b/src/frontend/parse-bison.y
@@ -29,7 +29,7 @@
   static void PPerror (YYLTYPE *locp, char **line, struct pnode **retval, char const *);
 %}
 
-%name-prefix="PP"
+%name-prefix "PP"
 
 %defines
 %locations
diff --git a/src/spicelib/parser/inpptree-parser.y b/src/spicelib/parser/inpptree-parser.y
index 500b43123..127a961f0 100644
--- a/src/spicelib/parser/inpptree-parser.y
+++ b/src/spicelib/parser/inpptree-parser.y
@@ -28,7 +28,7 @@
   static void PTerror (YYLTYPE *locp, char **line, struct INPparseNode **retval, void *ckt, char const *);
 %}
 
-%name-prefix="PT"
+%name-prefix "PT"
 
 %defines