diff --git a/src/dump.c b/src/dump.c
index 4a64aa4..5a76630 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -101,7 +101,7 @@ static int dump_indent(size_t flags, int depth, int space, json_dump_callback_t
 static int dump_string(const char *str, size_t len, json_dump_callback_t dump, void *data, size_t flags)
 {
     const char *pos, *end, *lim;
-    int32_t codepoint;
+    int32_t codepoint = 0;
 
     if(dump("\"", 1, data))
         return -1;
@@ -351,7 +351,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                 }
                 assert(i == size);
 
-                qsort(keys, size, sizeof(const char *), compare_keys);
+                qsort((void*)keys, size, sizeof(const char *), compare_keys);
 
                 for(i = 0; i < size; i++)
                 {
@@ -366,7 +366,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                     if(dump(separator, separator_length, data) ||
                        do_dump(value, flags, depth + 1, parents, dump, data))
                     {
-                        jsonp_free(keys);
+                        jsonp_free((void*)keys);
                         return -1;
                     }
 
@@ -375,7 +375,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                         if(dump(",", 1, data) ||
                            dump_indent(flags, depth + 1, 1, dump, data))
                         {
-                            jsonp_free(keys);
+                            jsonp_free((void*)keys);
                             return -1;
                         }
                     }
@@ -383,7 +383,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                     {
                         if(dump_indent(flags, depth, 0, dump, data))
                         {
-                            jsonp_free(keys);
+                            jsonp_free((void*)keys);
                             return -1;
                         }
                     }
diff --git a/src/hashtable_seed.c b/src/hashtable_seed.c
index 8aed540..540358a 100644
--- a/src/hashtable_seed.c
+++ b/src/hashtable_seed.c
@@ -164,7 +164,7 @@ static int seed_from_timestamp_and_pid(uint32_t *seed) {
 }
 
 static uint32_t generate_seed() {
-    uint32_t seed;
+    uint32_t seed = 0;
     int done = 0;
 
 #if !defined(_WIN32) && defined(USE_URANDOM)
diff --git a/src/load.c b/src/load.c
index 25efe2e..27d473e 100644
--- a/src/load.c
+++ b/src/load.c
@@ -174,7 +174,7 @@ static int stream_get(stream_t *stream, json_error_t *error)
             return STREAM_STATE_EOF;
         }
 
-        stream->buffer[0] = c;
+        stream->buffer[0] = (char) c;
         stream->buffer_pos = 0;
 
         if(0x80 <= c && c <= 0xFF)
@@ -189,7 +189,7 @@ static int stream_get(stream_t *stream, json_error_t *error)
             assert(count >= 2);
 
             for(i = 1; i < count; i++)
-                stream->buffer[i] = stream->get(stream->data);
+                stream->buffer[i] = (char) stream->get(stream->data);
 
             if(!utf8_check_full(stream->buffer, count, NULL))
                 goto out;
diff --git a/src/value.c b/src/value.c
index 861dce8..3f964a0 100644
--- a/src/value.c
+++ b/src/value.c
@@ -1044,8 +1044,6 @@ json_t *json_copy(json_t *json)
         default:
             return NULL;
     }
-
-    return NULL;
 }
 
 json_t *json_deep_copy(const json_t *json)
@@ -1073,6 +1071,4 @@ json_t *json_deep_copy(const json_t *json)
         default:
             return NULL;
     }
-
-    return NULL;
 }