diff --git a/src/debug.c b/src/debug.c
index 1e179caf..f3e10947 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -550,7 +550,7 @@ void debugCommand(client *c) {
 
 /* =========================== Crash handling  ============================== */
 
-void _serverAssert(char *estr, char *file, int line) {
+void _serverAssert(const char *estr, const char *file, int line) {
     bugReportStart();
     serverLog(LL_WARNING,"=== ASSERTION FAILED ===");
     serverLog(LL_WARNING,"==> %s:%d '%s' is not true",file,line,estr);
@@ -563,7 +563,7 @@ void _serverAssert(char *estr, char *file, int line) {
     *((char*)-1) = 'x';
 }
 
-void _serverAssertPrintClientInfo(client *c) {
+void _serverAssertPrintClientInfo(const client *c) {
     int j;
 
     bugReportStart();
@@ -587,7 +587,7 @@ void _serverAssertPrintClientInfo(client *c) {
     }
 }
 
-void serverLogObjectDebugInfo(robj *o) {
+void serverLogObjectDebugInfo(const robj *o) {
     serverLog(LL_WARNING,"Object type: %d", o->type);
     serverLog(LL_WARNING,"Object encoding: %d", o->encoding);
     serverLog(LL_WARNING,"Object refcount: %d", o->refcount);
@@ -607,23 +607,23 @@ void serverLogObjectDebugInfo(robj *o) {
     } else if (o->type == OBJ_ZSET) {
         serverLog(LL_WARNING,"Sorted set size: %d", (int) zsetLength(o));
         if (o->encoding == OBJ_ENCODING_SKIPLIST)
-            serverLog(LL_WARNING,"Skiplist level: %d", (int) ((zset*)o->ptr)->zsl->level);
+            serverLog(LL_WARNING,"Skiplist level: %d", (int) ((const zset*)o->ptr)->zsl->level);
     }
 }
 
-void _serverAssertPrintObject(robj *o) {
+void _serverAssertPrintObject(const robj *o) {
     bugReportStart();
     serverLog(LL_WARNING,"=== ASSERTION FAILED OBJECT CONTEXT ===");
     serverLogObjectDebugInfo(o);
 }
 
-void _serverAssertWithInfo(client *c, robj *o, char *estr, char *file, int line) {
+void _serverAssertWithInfo(const client *c, const robj *o, const char *estr, const char *file, int line) {
     if (c) _serverAssertPrintClientInfo(c);
     if (o) _serverAssertPrintObject(o);
     _serverAssert(estr,file,line);
 }
 
-void _serverPanic(char *msg, char *file, int line) {
+void _serverPanic(const char *msg, const char *file, int line) {
     bugReportStart();
     serverLog(LL_WARNING,"------------------------------------------------");
     serverLog(LL_WARNING,"!!! Software Failure. Press left mouse button to continue");
diff --git a/src/intset.c b/src/intset.c
index b0a597fc..30ea8534 100644
--- a/src/intset.c
+++ b/src/intset.c
@@ -272,7 +272,7 @@ uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value) {
 }
 
 /* Return intset length */
-uint32_t intsetLen(intset *is) {
+uint32_t intsetLen(const intset *is) {
     return intrev32ifbe(is->length);
 }
 
diff --git a/src/intset.h b/src/intset.h
index 30a854f8..8119e663 100644
--- a/src/intset.h
+++ b/src/intset.h
@@ -44,7 +44,7 @@ intset *intsetRemove(intset *is, int64_t value, int *success);
 uint8_t intsetFind(intset *is, int64_t value);
 int64_t intsetRandom(intset *is);
 uint8_t intsetGet(intset *is, uint32_t pos, int64_t *value);
-uint32_t intsetLen(intset *is);
+uint32_t intsetLen(const intset *is);
 size_t intsetBlobLen(intset *is);
 
 #ifdef REDIS_TEST
diff --git a/src/module.c b/src/module.c
index 54f27907..65063338 100644
--- a/src/module.c
+++ b/src/module.c
@@ -687,7 +687,7 @@ void RM_FreeString(RedisModuleCtx *ctx, RedisModuleString *str) {
 /* Given a string module object, this function returns the string pointer
  * and length of the string. The returned pointer and length should only
  * be used for read only accesses and never modified. */
-const char *RM_StringPtrLen(RedisModuleString *str, size_t *len) {
+const char *RM_StringPtrLen(const RedisModuleString *str, size_t *len) {
     if (len) *len = sdslen(str->ptr);
     return str->ptr;
 }
@@ -696,7 +696,7 @@ const char *RM_StringPtrLen(RedisModuleString *str, size_t *len) {
  * Returns REDISMODULE_OK on success. If the string can't be parsed
  * as a valid, strict long long (no spaces before/after), REDISMODULE_ERR
  * is returned. */
-int RM_StringToLongLong(RedisModuleString *str, long long *ll) {
+int RM_StringToLongLong(const RedisModuleString *str, long long *ll) {
     return string2ll(str->ptr,sdslen(str->ptr),ll) ? REDISMODULE_OK :
                                                      REDISMODULE_ERR;
 }
@@ -704,7 +704,7 @@ int RM_StringToLongLong(RedisModuleString *str, long long *ll) {
 /* Convert the string into a double, storing it at `*d`.
  * Returns REDISMODULE_OK on success or REDISMODULE_ERR if the string is
  * not a valid string representation of a double value. */
-int RM_StringToDouble(RedisModuleString *str, double *d) {
+int RM_StringToDouble(const RedisModuleString *str, double *d) {
     int retval = getDoubleFromObject(str,d);
     return (retval == C_OK) ? REDISMODULE_OK : REDISMODULE_ERR;
 }
diff --git a/src/object.c b/src/object.c
index b9e5667e..9d1d4b7e 100644
--- a/src/object.c
+++ b/src/object.c
@@ -539,7 +539,7 @@ size_t stringObjectLen(robj *o) {
     }
 }
 
-int getDoubleFromObject(robj *o, double *target) {
+int getDoubleFromObject(const robj *o, double *target) {
     double value;
     char *eptr;
 
@@ -550,7 +550,7 @@ int getDoubleFromObject(robj *o, double *target) {
         if (sdsEncodedObject(o)) {
             errno = 0;
             value = strtod(o->ptr, &eptr);
-            if (isspace(((char*)o->ptr)[0]) ||
+            if (isspace(((const char*)o->ptr)[0]) ||
                 eptr[0] != '\0' ||
                 (errno == ERANGE &&
                     (value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
diff --git a/src/quicklist.c b/src/quicklist.c
index be02e327..adf9ba1d 100644
--- a/src/quicklist.c
+++ b/src/quicklist.c
@@ -149,7 +149,7 @@ REDIS_STATIC quicklistNode *quicklistCreateNode(void) {
 }
 
 /* Return cached quicklist count */
-unsigned int quicklistCount(quicklist *ql) { return ql->count; }
+unsigned int quicklistCount(const quicklist *ql) { return ql->count; }
 
 /* Free entire quicklist. */
 void quicklistRelease(quicklist *quicklist) {
diff --git a/src/quicklist.h b/src/quicklist.h
index e040368e..8f387590 100644
--- a/src/quicklist.h
+++ b/src/quicklist.h
@@ -154,7 +154,7 @@ int quicklistPopCustom(quicklist *quicklist, int where, unsigned char **data,
                        void *(*saver)(unsigned char *data, unsigned int sz));
 int quicklistPop(quicklist *quicklist, int where, unsigned char **data,
                  unsigned int *sz, long long *slong);
-unsigned int quicklistCount(quicklist *ql);
+unsigned int quicklistCount(const quicklist *ql);
 int quicklistCompare(unsigned char *p1, unsigned char *p2, int p2_len);
 size_t quicklistGetLzf(const quicklistNode *node, void **data);
 
diff --git a/src/redismodule.h b/src/redismodule.h
index 618b39e4..6151e9fe 100644
--- a/src/redismodule.h
+++ b/src/redismodule.h
@@ -123,7 +123,7 @@ RedisModuleCallReply *REDISMODULE_API_FUNC(RedisModule_CallReplyArrayElement)(Re
 RedisModuleString *REDISMODULE_API_FUNC(RedisModule_CreateString)(RedisModuleCtx *ctx, const char *ptr, size_t len);
 RedisModuleString *REDISMODULE_API_FUNC(RedisModule_CreateStringFromLongLong)(RedisModuleCtx *ctx, long long ll);
 void REDISMODULE_API_FUNC(RedisModule_FreeString)(RedisModuleCtx *ctx, RedisModuleString *str);
-const char *REDISMODULE_API_FUNC(RedisModule_StringPtrLen)(RedisModuleString *str, size_t *len);
+const char *REDISMODULE_API_FUNC(RedisModule_StringPtrLen)(const RedisModuleString *str, size_t *len);
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithError)(RedisModuleCtx *ctx, const char *err);
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithSimpleString)(RedisModuleCtx *ctx, const char *msg);
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithArray)(RedisModuleCtx *ctx, long len);
@@ -133,8 +133,8 @@ int REDISMODULE_API_FUNC(RedisModule_ReplyWithString)(RedisModuleCtx *ctx, Redis
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithNull)(RedisModuleCtx *ctx);
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithDouble)(RedisModuleCtx *ctx, double d);
 int REDISMODULE_API_FUNC(RedisModule_ReplyWithCallReply)(RedisModuleCtx *ctx, RedisModuleCallReply *reply);
-int REDISMODULE_API_FUNC(RedisModule_StringToLongLong)(RedisModuleString *str, long long *ll);
-int REDISMODULE_API_FUNC(RedisModule_StringToDouble)(RedisModuleString *str, double *d);
+int REDISMODULE_API_FUNC(RedisModule_StringToLongLong)(const RedisModuleString *str, long long *ll);
+int REDISMODULE_API_FUNC(RedisModule_StringToDouble)(const RedisModuleString *str, double *d);
 void REDISMODULE_API_FUNC(RedisModule_AutoMemory)(RedisModuleCtx *ctx);
 int REDISMODULE_API_FUNC(RedisModule_Replicate)(RedisModuleCtx *ctx, const char *cmdname, const char *fmt, ...);
 int REDISMODULE_API_FUNC(RedisModule_ReplicateVerbatim)(RedisModuleCtx *ctx);
diff --git a/src/server.h b/src/server.h
index 10fbf323..cd5ac77f 100644
--- a/src/server.h
+++ b/src/server.h
@@ -1048,8 +1048,8 @@ struct redisServer {
     long long latency_monitor_threshold;
     dict *latency_events;
     /* Assert & bug reporting */
-    char *assert_failed;
-    char *assert_file;
+    const char *assert_failed;
+    const char *assert_file;
     int assert_line;
     int bug_report_start; /* True if bug report header was already logged. */
     int watchdog_period;  /* Software watchdog period in ms. 0 = off */
@@ -1245,7 +1245,7 @@ void addReplyStatusFormat(client *c, const char *fmt, ...);
 void listTypeTryConversion(robj *subject, robj *value);
 void listTypePush(robj *subject, robj *value, int where);
 robj *listTypePop(robj *subject, int where);
-unsigned long listTypeLength(robj *subject);
+unsigned long listTypeLength(const robj *subject);
 listTypeIterator *listTypeInitIterator(robj *subject, long index, unsigned char direction);
 void listTypeReleaseIterator(listTypeIterator *li);
 int listTypeNext(listTypeIterator *li, listTypeEntry *entry);
@@ -1305,7 +1305,7 @@ int getLongFromObjectOrReply(client *c, robj *o, long *target, const char *msg);
 int checkType(client *c, robj *o, int type);
 int getLongLongFromObjectOrReply(client *c, robj *o, long long *target, const char *msg);
 int getDoubleFromObjectOrReply(client *c, robj *o, double *target, const char *msg);
-int getDoubleFromObject(robj *o, double *target);
+int getDoubleFromObject(const robj *o, double *target);
 int getLongLongFromObject(robj *o, long long *target);
 int getLongDoubleFromObject(robj *o, long double *target);
 int getLongDoubleFromObjectOrReply(client *c, robj *o, long double *target, const char *msg);
@@ -1406,7 +1406,7 @@ void zzlNext(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);
 void zzlPrev(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);
 unsigned char *zzlFirstInRange(unsigned char *zl, zrangespec *range);
 unsigned char *zzlLastInRange(unsigned char *zl, zrangespec *range);
-unsigned int zsetLength(robj *zobj);
+unsigned int zsetLength(const robj *zobj);
 void zsetConvert(robj *zobj, int encoding);
 void zsetConvertToZiplistIfNeeded(robj *zobj, size_t maxelelen);
 int zsetScore(robj *zobj, sds member, double *score);
@@ -1479,7 +1479,7 @@ int setTypeNext(setTypeIterator *si, sds *sdsele, int64_t *llele);
 sds setTypeNextObject(setTypeIterator *si);
 int setTypeRandomElement(robj *setobj, sds *sdsele, int64_t *llele);
 unsigned long setTypeRandomElements(robj *set, unsigned long count, robj *aux_set);
-unsigned long setTypeSize(robj *subject);
+unsigned long setTypeSize(const robj *subject);
 void setTypeConvert(robj *subject, int enc);
 
 /* Hash data type */
@@ -1492,7 +1492,7 @@ void hashTypeTryConversion(robj *subject, robj **argv, int start, int end);
 void hashTypeTryObjectEncoding(robj *subject, robj **o1, robj **o2);
 int hashTypeExists(robj *o, sds key);
 int hashTypeDelete(robj *o, sds key);
-unsigned long hashTypeLength(robj *o);
+unsigned long hashTypeLength(const robj *o);
 hashTypeIterator *hashTypeInitIterator(robj *subject);
 void hashTypeReleaseIterator(hashTypeIterator *hi);
 int hashTypeNext(hashTypeIterator *hi);
@@ -1799,11 +1799,11 @@ void *realloc(void *ptr, size_t size) __attribute__ ((deprecated));
 #endif
 
 /* Debugging stuff */
-void _serverAssertWithInfo(client *c, robj *o, char *estr, char *file, int line);
-void _serverAssert(char *estr, char *file, int line);
-void _serverPanic(char *msg, char *file, int line);
+void _serverAssertWithInfo(const client *c, const robj *o, const char *estr, const char *file, int line);
+void _serverAssert(const char *estr, const char *file, int line);
+void _serverPanic(const char *msg, const char *file, int line);
 void bugReportStart(void);
-void serverLogObjectDebugInfo(robj *o);
+void serverLogObjectDebugInfo(const robj *o);
 void sigsegvHandler(int sig, siginfo_t *info, void *secret);
 sds genRedisInfoString(char *section);
 void enableWatchdog(int period);
diff --git a/src/t_hash.c b/src/t_hash.c
index c75b391d..a4955933 100644
--- a/src/t_hash.c
+++ b/src/t_hash.c
@@ -308,13 +308,13 @@ int hashTypeDelete(robj *o, sds field) {
 }
 
 /* Return the number of elements in a hash. */
-unsigned long hashTypeLength(robj *o) {
+unsigned long hashTypeLength(const robj *o) {
     unsigned long length = ULONG_MAX;
 
     if (o->encoding == OBJ_ENCODING_ZIPLIST) {
         length = ziplistLen(o->ptr) / 2;
     } else if (o->encoding == OBJ_ENCODING_HT) {
-        length = dictSize((dict*)o->ptr);
+        length = dictSize((const dict*)o->ptr);
     } else {
         serverPanic("Unknown hash encoding");
     }
diff --git a/src/t_list.c b/src/t_list.c
index f9969fa2..a0a30998 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -71,7 +71,7 @@ robj *listTypePop(robj *subject, int where) {
     return value;
 }
 
-unsigned long listTypeLength(robj *subject) {
+unsigned long listTypeLength(const robj *subject) {
     if (subject->encoding == OBJ_ENCODING_QUICKLIST) {
         return quicklistCount(subject->ptr);
     } else {
diff --git a/src/t_set.c b/src/t_set.c
index db5c544b..ddd82b8b 100644
--- a/src/t_set.c
+++ b/src/t_set.c
@@ -219,11 +219,11 @@ int setTypeRandomElement(robj *setobj, sds *sdsele, int64_t *llele) {
     return setobj->encoding;
 }
 
-unsigned long setTypeSize(robj *subject) {
+unsigned long setTypeSize(const robj *subject) {
     if (subject->encoding == OBJ_ENCODING_HT) {
-        return dictSize((dict*)subject->ptr);
+        return dictSize((const dict*)subject->ptr);
     } else if (subject->encoding == OBJ_ENCODING_INTSET) {
-        return intsetLen((intset*)subject->ptr);
+        return intsetLen((const intset*)subject->ptr);
     } else {
         serverPanic("Unknown set encoding");
     }
diff --git a/src/t_zset.c b/src/t_zset.c
index 7c96cf63..c61ba808 100644
--- a/src/t_zset.c
+++ b/src/t_zset.c
@@ -1100,12 +1100,12 @@ unsigned char *zzlDeleteRangeByRank(unsigned char *zl, unsigned int start, unsig
  * Common sorted set API
  *----------------------------------------------------------------------------*/
 
-unsigned int zsetLength(robj *zobj) {
+unsigned int zsetLength(const robj *zobj) {
     int length = -1;
     if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
         length = zzlLength(zobj->ptr);
     } else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
-        length = ((zset*)zobj->ptr)->zsl->length;
+        length = ((const zset*)zobj->ptr)->zsl->length;
     } else {
         serverPanic("Unknown sorted set encoding");
     }