diff --git a/src/module.c b/src/module.c
index b7108cd6d..8fdbf2ccb 100644
--- a/src/module.c
+++ b/src/module.c
@@ -2559,19 +2559,14 @@ int RM_StringTruncate(RedisModuleKey *key, size_t newlen) {
     } else {
         /* Unshare and resize. */
         key->value = dbUnshareStringValue(key->db, key->key, key->value);
-        if (newlen == 0) {
-            sdsfree(key->value->ptr);
-            key->value->ptr = sdsempty();
-        } else {
-            size_t curlen = sdslen(key->value->ptr);
-            if (newlen > curlen) {
-                key->value->ptr = sdsgrowzero(key->value->ptr,newlen);
-            } else if (newlen < curlen) {
-                sdsrange(key->value->ptr,0,newlen-1);
-                /* If the string is too wasteful, reallocate it. */
-                if (sdslen(key->value->ptr) < sdsavail(key->value->ptr))
-                    key->value->ptr = sdsRemoveFreeSpace(key->value->ptr);
-            }
+        size_t curlen = sdslen(key->value->ptr);
+        if (newlen > curlen) {
+            key->value->ptr = sdsgrowzero(key->value->ptr,newlen);
+        } else if (newlen < curlen) {
+            sdssubstr(key->value->ptr,0,newlen);
+            /* If the string is too wasteful, reallocate it. */
+            if (sdslen(key->value->ptr) < sdsavail(key->value->ptr))
+                key->value->ptr = sdsRemoveFreeSpace(key->value->ptr);
         }
     }
     return REDISMODULE_OK;
diff --git a/src/sds.c b/src/sds.c
index 31ab2ed3a..036d714d4 100644
--- a/src/sds.c
+++ b/src/sds.c
@@ -778,6 +778,21 @@ sds sdstrim(sds s, const char *cset) {
     return s;
 }
 
+/* Changes the input string to be a subset of the original.
+ * It does not release the free space in the string, so a call to
+ * sdsRemoveFreeSpace may be wise after. */
+void sdssubstr(sds s, size_t start, size_t len) {
+    /* Clamp out of range input */
+    size_t oldlen = sdslen(s);
+    if (start >= oldlen) start = len = 0;
+    if (len > oldlen-start) len = oldlen-start;
+
+    /* Move the data */
+    if (len) memmove(s, s+start, len);
+    s[len] = 0;
+    sdssetlen(s,len);
+}
+
 /* Turn the string into a smaller (or equal) string containing only the
  * substring specified by the 'start' and 'end' indexes.
  *
@@ -789,6 +804,11 @@ sds sdstrim(sds s, const char *cset) {
  *
  * The string is modified in-place.
  *
+ * NOTE: this function can be misleading and can have unexpected behaviour,
+ * specifically when you want the length of the new string to be 0.
+ * Having start==end will result in a string with one character.
+ * please consider using sdssubstr instead.
+ *
  * Example:
  *
  * s = sdsnew("Hello World");
@@ -796,28 +816,13 @@ sds sdstrim(sds s, const char *cset) {
  */
 void sdsrange(sds s, ssize_t start, ssize_t end) {
     size_t newlen, len = sdslen(s);
-
     if (len == 0) return;
-    if (start < 0) {
-        start = len+start;
-        if (start < 0) start = 0;
-    }
-    if (end < 0) {
-        end = len+end;
-        if (end < 0) end = 0;
-    }
+    if (start < 0)
+        start = len + start;
+    if (end < 0)
+        end = len + end;
     newlen = (start > end) ? 0 : (end-start)+1;
-    if (newlen != 0) {
-        if (start >= (ssize_t)len) {
-            newlen = 0;
-        } else if (end >= (ssize_t)len) {
-            end = len-1;
-            newlen = (end-start)+1;
-        }
-    }
-    if (start && newlen) memmove(s, s+start, newlen);
-    s[newlen] = 0;
-    sdssetlen(s,newlen);
+    sdssubstr(s, start, newlen);
 }
 
 /* Apply tolower() to every character of the sds string 's'. */
@@ -1372,6 +1377,18 @@ int sdsTest(int argc, char **argv, int accurate) {
         test_cond("sdsrange(...,100,100)",
             sdslen(y) == 0 && memcmp(y,"\0",1) == 0);
 
+        sdsfree(y);
+        y = sdsdup(x);
+        sdsrange(y,4,6);
+        test_cond("sdsrange(...,4,6)",
+            sdslen(y) == 0 && memcmp(y,"\0",1) == 0);
+
+        sdsfree(y);
+        y = sdsdup(x);
+        sdsrange(y,3,6);
+        test_cond("sdsrange(...,3,6)",
+            sdslen(y) == 1 && memcmp(y,"o\0",2) == 0);
+
         sdsfree(y);
         sdsfree(x);
         x = sdsnew("foo");
diff --git a/src/sds.h b/src/sds.h
index 8392c2064..9b01b4e4e 100644
--- a/src/sds.h
+++ b/src/sds.h
@@ -238,6 +238,7 @@ sds sdscatprintf(sds s, const char *fmt, ...);
 
 sds sdscatfmt(sds s, char const *fmt, ...);
 sds sdstrim(sds s, const char *cset);
+void sdssubstr(sds s, size_t start, size_t len);
 void sdsrange(sds s, ssize_t start, ssize_t end);
 void sdsupdatelen(sds s);
 void sdsclear(sds s);
diff --git a/tests/modules/basics.c b/tests/modules/basics.c
index 9786be1b9..2618f45b8 100644
--- a/tests/modules/basics.c
+++ b/tests/modules/basics.c
@@ -156,6 +156,7 @@ int TestUnlink(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
 
 /* TEST.STRING.TRUNCATE -- Test truncating an existing string object. */
 int TestStringTruncate(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx);
     REDISMODULE_NOT_USED(argv);
     REDISMODULE_NOT_USED(argc);
 
@@ -208,6 +209,7 @@ int TestStringTruncate(RedisModuleCtx *ctx, RedisModuleString **argv, int argc)
 
 int NotifyCallback(RedisModuleCtx *ctx, int type, const char *event,
                    RedisModuleString *key) {
+  RedisModule_AutoMemory(ctx);
   /* Increment a counter on the notifications: for each key notified we
    * increment a counter */
   RedisModule_Log(ctx, "notice", "Got event type %d, event %s, key %s", type,
@@ -219,6 +221,7 @@ int NotifyCallback(RedisModuleCtx *ctx, int type, const char *event,
 
 /* TEST.NOTIFICATIONS -- Test Keyspace Notifications. */
 int TestNotifications(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
+    RedisModule_AutoMemory(ctx);
     REDISMODULE_NOT_USED(argv);
     REDISMODULE_NOT_USED(argc);