diff --git a/contrib/cube/cubeparse.y b/contrib/cube/cubeparse.y
index b39fbe63e6b..fd56d0e1628 100644
--- a/contrib/cube/cubeparse.y
+++ b/contrib/cube/cubeparse.y
@@ -11,6 +11,10 @@
 #include "utils/float.h"
 #include "varatt.h"
 
+/* silence -Wmissing-variable-declarations */
+extern int cube_yychar;
+extern int cube_yynerrs;
+
 /* All grammar constructs return strings */
 #define YYSTYPE char *
 
diff --git a/contrib/seg/segparse.y b/contrib/seg/segparse.y
index bf759dbbd84..729d4b6390b 100644
--- a/contrib/seg/segparse.y
+++ b/contrib/seg/segparse.y
@@ -13,6 +13,10 @@
 
 #include "segdata.h"
 
+/* silence -Wmissing-variable-declarations */
+extern int seg_yychar;
+extern int seg_yynerrs;
+
 /*
  * Bison doesn't allocate anything that needs to live across parser calls,
  * so we can easily have it use palloc instead of malloc.  This prevents
diff --git a/src/backend/bootstrap/bootparse.y b/src/backend/bootstrap/bootparse.y
index 3c9c1da0216..58e0878dc8d 100644
--- a/src/backend/bootstrap/bootparse.y
+++ b/src/backend/bootstrap/bootparse.y
@@ -33,6 +33,11 @@
 #include "utils/memutils.h"
 
 
+/* silence -Wmissing-variable-declarations */
+extern int boot_yychar;
+extern int boot_yynerrs;
+
+
 /*
  * Bison doesn't allocate anything that needs to live across parser calls,
  * so we can easily have it use palloc instead of malloc.  This prevents
diff --git a/src/backend/replication/repl_gram.y b/src/backend/replication/repl_gram.y
index 53780bbf297..c46ca395263 100644
--- a/src/backend/replication/repl_gram.y
+++ b/src/backend/replication/repl_gram.y
@@ -23,6 +23,11 @@
 #include "replication/walsender_private.h"
 
 
+/* silence -Wmissing-variable-declarations */
+extern int replication_yychar;
+extern int replication_yynerrs;
+
+
 /* Result of the parsing is returned here */
 Node *replication_parse_result;
 
diff --git a/src/backend/replication/syncrep_gram.y b/src/backend/replication/syncrep_gram.y
index a14f63b6582..5ce4f1bfe73 100644
--- a/src/backend/replication/syncrep_gram.y
+++ b/src/backend/replication/syncrep_gram.y
@@ -24,6 +24,10 @@ char	   *syncrep_parse_error_msg;
 static SyncRepConfigData *create_syncrep_config(const char *num_sync,
 					List *members, uint8 syncrep_method);
 
+/* silence -Wmissing-variable-declarations */
+extern int syncrep_yychar;
+extern int syncrep_yynerrs;
+
 /*
  * Bison doesn't allocate anything that needs to live across parser calls,
  * so we can easily have it use palloc instead of malloc.  This prevents
diff --git a/src/interfaces/ecpg/preproc/ecpg.header b/src/interfaces/ecpg/preproc/ecpg.header
index 59502894256..571b92f6434 100644
--- a/src/interfaces/ecpg/preproc/ecpg.header
+++ b/src/interfaces/ecpg/preproc/ecpg.header
@@ -8,6 +8,10 @@
 #include "ecpg_config.h"
 #include <unistd.h>
 
+/* silence -Wmissing-variable-declarations */
+extern int base_yychar;
+extern int base_yynerrs;
+
 /* Location tracking support --- simpler than bison's default */
 #define YYLLOC_DEFAULT(Current, Rhs, N) \
 	do { \
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 97be9239e37..0671ff78722 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -27,6 +27,10 @@
 #include "plpgsql.h"
 
 
+/* silence -Wmissing-variable-declarations */
+extern int plpgsql_yychar;
+extern int plpgsql_yynerrs;
+
 /* Location tracking support --- simpler than bison's default */
 #define YYLLOC_DEFAULT(Current, Rhs, N) \
 	do { \
diff --git a/src/test/isolation/specparse.y b/src/test/isolation/specparse.y
index 0e8b166a53e..282a7504556 100644
--- a/src/test/isolation/specparse.y
+++ b/src/test/isolation/specparse.y
@@ -14,6 +14,9 @@
 
 #include "isolationtester.h"
 
+/* silence -Wmissing-variable-declarations */
+extern int spec_yychar;
+extern int spec_yynerrs;
 
 TestSpec		parseresult;			/* result of parsing is left here */