diff --git a/src/object.c b/src/object.c
index fd7786ed6e463a8ec6b1e225857b166a4f307244..d74fc96507f1f8e03dd89b17d70e9fc14857c21d 100644
--- a/src/object.c
+++ b/src/object.c
@@ -44,6 +44,21 @@ robj *createStringObjectFromLongLong(long long value) {
     return o;
 }
 
+/* Note: this function is defined into object.c since here it is where it
+ * belongs but it is actually designed to be used just for INCRBYFLOAT */
+robj *createStringObjectFromLongDouble(long double value) {
+    char buf[256];
+    int len;
+
+    /* We use 17 digits precision since with 128 bit floats that precision
+     * after rouding is able to represent most small decimal numbers in a way
+     * that is "non surprising" for the user (that is, most small decimal
+     * numbers will be represented in a way that when converted back into
+     * a string are exactly the same as what the user typed.) */
+    len = snprintf(buf,sizeof(buf),"%.17Lg", value);
+    return createStringObject(buf,len);
+}
+
 robj *dupStringObject(robj *o) {
     redisAssertWithInfo(NULL,o,o->encoding == REDIS_ENCODING_RAW);
     return createStringObject(o->ptr,sdslen(o->ptr));
@@ -350,8 +365,10 @@ int getDoubleFromObject(robj *o, double *target) {
     } else {
         redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
         if (o->encoding == REDIS_ENCODING_RAW) {
+            errno = 0;
             value = strtod(o->ptr, &eptr);
-            if (eptr[0] != '\0' || isnan(value)) return REDIS_ERR;
+            if (eptr[0] != '\0' || errno == ERANGE || isnan(value))
+                return REDIS_ERR;
         } else if (o->encoding == REDIS_ENCODING_INT) {
             value = (long)o->ptr;
         } else {
@@ -369,7 +386,45 @@ int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const ch
         if (msg != NULL) {
             addReplyError(c,(char*)msg);
         } else {
-            addReplyError(c,"value is not a double");
+            addReplyError(c,"value is not a valid float");
+        }
+        return REDIS_ERR;
+    }
+
+    *target = value;
+    return REDIS_OK;
+}
+
+int getLongDoubleFromObject(robj *o, long double *target) {
+    long double value;
+    char *eptr;
+
+    if (o == NULL) {
+        value = 0;
+    } else {
+        redisAssertWithInfo(NULL,o,o->type == REDIS_STRING);
+        if (o->encoding == REDIS_ENCODING_RAW) {
+            errno = 0;
+            value = strtold(o->ptr, &eptr);
+            if (eptr[0] != '\0' || errno == ERANGE || isnan(value))
+                return REDIS_ERR;
+        } else if (o->encoding == REDIS_ENCODING_INT) {
+            value = (long)o->ptr;
+        } else {
+            redisPanic("Unknown string encoding");
+        }
+    }
+    *target = value;
+    return REDIS_OK;
+}
+
+int getLongDoubleFromObjectOrReply(redisClient *c, robj *o, long double *target, const char *msg) {
+    long double value;
+    if (getLongDoubleFromObject(o, &value) != REDIS_OK) {
+        if (msg != NULL) {
+            addReplyError(c,(char*)msg);
+        } else {
+            addReplyError(c,"value is not a valid float");
         }
         return REDIS_ERR;
     }
diff --git a/src/redis.c b/src/redis.c
index 7d2094390c8a37363faf845200836c32d20cca5a..527b053852e1b14401837c4e645707985ebe5bc1 100644
--- a/src/redis.c
+++ b/src/redis.c
@@ -165,6 +165,7 @@ struct redisCommand redisCommandTable[] = {
     {"hexists",hexistsCommand,3,"r",0,NULL,1,1,1,0,0},
     {"incrby",incrbyCommand,3,"wm",0,NULL,1,1,1,0,0},
     {"decrby",decrbyCommand,3,"wm",0,NULL,1,1,1,0,0},
+    {"incrbyfloat",incrbyfloatCommand,3,"wm",0,NULL,1,1,1,0,0},
     {"getset",getsetCommand,3,"wm",0,NULL,1,1,1,0,0},
     {"mset",msetCommand,-3,"wm",0,NULL,1,-1,2,0,0},
     {"msetnx",msetnxCommand,-3,"wm",0,NULL,1,-1,2,0,0},
diff --git a/src/redis.h b/src/redis.h
index d660cae91b3b17f6257321814cd6021d0e76da60..0024792cc11850e722fa3820ef4b48aa5d47bfa9 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -811,6 +811,7 @@ robj *tryObjectEncoding(robj *o);
 robj *getDecodedObject(robj *o);
 size_t stringObjectLen(robj *o);
 robj *createStringObjectFromLongLong(long long value);
+robj *createStringObjectFromLongDouble(long double value);
 robj *createListObject(void);
 robj *createZiplistObject(void);
 robj *createSetObject(void);
@@ -823,6 +824,8 @@ int checkType(redisClient *c, robj *o, int type);
 int getLongLongFromObjectOrReply(redisClient *c, robj *o, long long *target, const char *msg);
 int getDoubleFromObjectOrReply(redisClient *c, robj *o, double *target, const char *msg);
 int getLongLongFromObject(robj *o, long long *target);
+int getLongDoubleFromObject(robj *o, long double *target);
+int getLongDoubleFromObjectOrReply(redisClient *c, robj *o, long double *target, const char *msg);
 char *strEncoding(int encoding);
 int compareStringObjects(robj *a, robj *b);
 int equalStringObjects(robj *a, robj *b);
@@ -1004,6 +1007,7 @@ void incrCommand(redisClient *c);
 void decrCommand(redisClient *c);
 void incrbyCommand(redisClient *c);
 void decrbyCommand(redisClient *c);
+void incrbyfloatCommand(redisClient *c);
 void selectCommand(redisClient *c);
 void randomkeyCommand(redisClient *c);
 void keysCommand(redisClient *c);
diff --git a/src/t_string.c b/src/t_string.c
index ce6233a98d3e8df653bc990f098eea0572d7f489..1f0b1fbcc44b49c60a4065c52f40bd53496e01d0 100644
--- a/src/t_string.c
+++ b/src/t_string.c
@@ -1,4 +1,5 @@
 #include "redis.h"
+#include <math.h> /* isnan(), isinf() */
 
 /*-----------------------------------------------------------------------------
  * String Commands
@@ -382,6 +383,31 @@ void decrbyCommand(redisClient *c) {
     incrDecrCommand(c,-incr);
 }
 
+void incrbyfloatCommand(redisClient *c) {
+    long double incr, value;
+    robj *o, *new;
+
+    o = lookupKeyWrite(c->db,c->argv[1]);
+    if (o != NULL && checkType(c,o,REDIS_STRING)) return;
+    if (getLongDoubleFromObjectOrReply(c,o,&value,NULL) != REDIS_OK ||
+        getLongDoubleFromObjectOrReply(c,c->argv[2],&incr,NULL) != REDIS_OK)
+        return;
+
+    value += incr;
+    if (isnan(value) || isinf(value)) {
+        addReplyError(c,"increment would produce NaN or Infinity");
+        return;
+    }
+    new = createStringObjectFromLongDouble(value);
+    if (o)
+        dbOverwrite(c->db,c->argv[1],new);
+    else
+        dbAdd(c->db,c->argv[1],new);
+    signalModifiedKey(c->db,c->argv[1]);
+    server.dirty++;
+    addReplyBulk(c,new);
+}
+
 void appendCommand(redisClient *c) {
     size_t totlen;
     robj *o, *append;