diff --git a/src/dump.c b/src/dump.c
index 2c7dee9..bbf87d0 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -38,7 +38,7 @@ static int dump_to_file(const char *buffer, size_t size, void *data)
 }
 
 /* 32 spaces (the maximum indentation size) */
-static char whitespace[] = "                                ";
+static const char whitespace[] = "                                ";
 
 static int dump_indent(size_t flags, int depth, int space, json_dump_callback_t dump, void *data)
 {
diff --git a/src/hashtable.c b/src/hashtable.c
index 76cf69b..bcbaa8c 100644
--- a/src/hashtable.c
+++ b/src/hashtable.c
@@ -74,7 +74,7 @@ static void insert_to_bucket(hashtable_t *hashtable, bucket_t *bucket,
     }
 }
 
-static size_t primes[] = {
+static const size_t primes[] = {
     5, 13, 23, 53, 97, 193, 389, 769, 1543, 3079, 6151, 12289, 24593,
     49157, 98317, 196613, 393241, 786433, 1572869, 3145739, 6291469,
     12582917, 25165843, 50331653, 100663319, 201326611, 402653189,
diff --git a/src/load.c b/src/load.c
index d88a704..bf6ee30 100644
--- a/src/load.c
+++ b/src/load.c
@@ -37,7 +37,7 @@
 #define l_isalpha(c)  (l_isupper(c) || l_islower(c))
 #define l_isdigit(c)  ('0' <= (c) && (c) <= '9')
 #define l_isxdigit(c) \
-    (l_isdigit(c) || 'A' <= (c) || (c) <= 'F' || 'a' <= (c) || (c) <= 'f')
+    (l_isdigit(c) || ('A' <= (c) && (c) <= 'F') || ('a' <= (c) && (c) <= 'f'))
 
 /* Read one byte from stream, convert to unsigned char, then int, and
    return. return EOF on end of file. This corresponds to the
diff --git a/src/pack_unpack.c b/src/pack_unpack.c
index 39db9b8..18f9ccb 100644
--- a/src/pack_unpack.c
+++ b/src/pack_unpack.c
@@ -21,7 +21,7 @@ typedef struct {
     int column;
 } scanner_t;
 
-static const char *type_names[] = {
+static const char * const type_names[] = {
     "object",
     "array",
     "string",
@@ -34,7 +34,7 @@ static const char *type_names[] = {
 
 #define type_name(x) type_names[json_typeof(x)]
 
-static const char *unpack_value_starters = "{[siIbfFOon";
+static const char unpack_value_starters[] = "{[siIbfFOon";
 
 
 static void scanner_init(scanner_t *s, json_error_t *error,