diff --git a/data/c.m4 b/data/c.m4
index fd2203eb..994d2964 100644
--- a/data/c.m4
+++ b/data/c.m4
@@ -184,7 +184,7 @@ m4_define([b4_table_value_equals],
 [m4_if(m4_eval($3 < m4_indir([b4_]$1[_min])
                || m4_indir([b4_]$1[_max]) < $3), [1],
        [[YYID (0)]],
-       [[((]$2[) == (]$3[))]])])
+       [(!!(($2) == ($3)))])])
 
 
 ## ---------##
diff --git a/data/glr.c b/data/glr.c
index 9b8ff67c..79d6ffd0 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -290,7 +290,8 @@ b4_percent_code_get[]dnl
 # include <setjmp.h>
 # define YYJMP_BUF jmp_buf
 # define YYSETJMP(Env) setjmp (Env)
-# define YYLONGJMP(Env, Val) longjmp (Env, Val)
+// Pacify clang.
+# define YYLONGJMP(Env, Val) (longjmp (Env, Val), YYASSERT (0))
 #endif
 
 /*-----------------.
diff --git a/src/uniqstr.h b/src/uniqstr.h
index 913da39f..677ecc42 100644
--- a/src/uniqstr.h
+++ b/src/uniqstr.h
@@ -36,7 +36,7 @@ uniqstr uniqstr_vsprintf (char const *format, ...)
   __attribute__ ((__format__ (__printf__, 1, 2)));
 
 /* Two uniqstr values have the same value iff they are the same.  */
-#define UNIQSTR_EQ(USTR1, USTR2) ((USTR1) == (USTR2))
+#define UNIQSTR_EQ(USTR1, USTR2) (!!((USTR1) == (USTR2)))
 
 /* Compare two uniqstr a la strcmp: negative for <, nul for =, and
    positive for >.  Undefined order, relies on addresses.  */