diff --git a/exporter.go b/exporter.go
index a1bdb42..54dcd32 100644
--- a/exporter.go
+++ b/exporter.go
@@ -518,7 +518,9 @@ func (e *Exporter) collectAccountTransactionsMetrics(wg *sync.WaitGroup, ch chan
 
 	// add 1 second to the last update time to avoid querying the same activity twice
 	minTime := account.Tx.LastUpdate.Add(time.Second * 1)
-	activities, err := heliumapi.GetActivityForAccount(account.Address, activityTypes, &minTime, nil)
+	// Explicitly set max_time, to avoid issues with server-side caching
+	maxTime := time.Now()
+	activities, err := heliumapi.GetActivityForAccount(account.Address, activityTypes, &minTime, &maxTime)
 	if err != nil {
 		log.Println(err)
 		return
diff --git a/heliumapi/accounts.go b/heliumapi/accounts.go
index 15b8266..92caaad 100644
--- a/heliumapi/accounts.go
+++ b/heliumapi/accounts.go
@@ -37,10 +37,10 @@ func GetActivityForAccount(account string, filterTypes []string, minTime *time.T
 		params["min_time"] = strings.Join(filterTypes, ",")
 	}
 	if minTime != nil {
-		params["min_time"] = minTime.UTC().Format(timeFormat)
+		params["min_time"] = minTime.UTC().Format(time.RFC3339)
 	}
 	if maxTime != nil {
-		params["max_time"] = maxTime.UTC().Format(timeFormat)
+		params["max_time"] = maxTime.UTC().Format(time.RFC3339)
 	}
 
 	// query the api
@@ -88,10 +88,10 @@ func GetRewardTotalsForAccount(account string, minTime *time.Time, maxTime *time
 	path := "/v1/accounts/" + account + "/rewards/sum"
 	params := map[string]string{}
 	if minTime != nil {
-		params["min_time"] = minTime.UTC().Format(timeFormat)
+		params["min_time"] = minTime.UTC().Format(time.RFC3339)
 	}
 	if maxTime != nil {
-		params["max_time"] = maxTime.UTC().Format(timeFormat)
+		params["max_time"] = maxTime.UTC().Format(time.RFC3339)
 	}
 
 	// query the api
diff --git a/heliumapi/block.go b/heliumapi/block.go
index c455452..51fa941 100644
--- a/heliumapi/block.go
+++ b/heliumapi/block.go
@@ -12,7 +12,7 @@ func GetHeight(maxTime *time.Time) (int, error) {
 	path := "/v1/blocks/height"
 	params := map[string]string{}
 	if maxTime != nil {
-		params["max_time"] = maxTime.UTC().Format(timeFormat)
+		params["max_time"] = maxTime.UTC().Format(time.RFC3339)
 	}
 
 	// query the api
diff --git a/heliumapi/hotspots.go b/heliumapi/hotspots.go
index 99d66b8..1ef9342 100644
--- a/heliumapi/hotspots.go
+++ b/heliumapi/hotspots.go
@@ -31,10 +31,10 @@ func GetRewardsTotalForHotspot(hotspot string, minTime *time.Time, maxTime *time
 	path := "/v1/hotspots/" + hotspot + "/rewards/sum"
 	params := map[string]string{}
 	if minTime != nil {
-		params["min_time"] = minTime.UTC().Format(timeFormat)
+		params["min_time"] = minTime.UTC().Format(time.RFC3339)
 	}
 	if maxTime != nil {
-		params["max_time"] = maxTime.UTC().Format(timeFormat)
+		params["max_time"] = maxTime.UTC().Format(time.RFC3339)
 	}
 
 	// query the api
diff --git a/heliumapi/query.go b/heliumapi/query.go
index 4f1772c..29506c3 100644
--- a/heliumapi/query.go
+++ b/heliumapi/query.go
@@ -6,7 +6,6 @@ import (
 	"io/ioutil"
 	"log"
 	"net/http"
-	"strings"
 )
 
 var (
diff --git a/heliumapi/types.go b/heliumapi/types.go
index 2e48596..23bc054 100644
--- a/heliumapi/types.go
+++ b/heliumapi/types.go
@@ -1,12 +1,5 @@
 package heliumapi
 
-const (
-	// WORKAROUND: for some reason, helium api partially breaks when given the timezone information
-	// in "max_time" and "min_time", even if the example code suggest that it supports it.
-	// For this reason, we cannot use time.RFC3339 as the time format.
-	timeFormat = "2006-01-02T15:04:05Z"
-)
-
 type AccountResp struct {
 	Data Account `json:"data"`
 }