diff --git a/src/MQTTAsync.c b/src/MQTTAsync.c
index c6a11f6d3..5e0d3f6a2 100644
--- a/src/MQTTAsync.c
+++ b/src/MQTTAsync.c
@@ -645,7 +645,7 @@ int MQTTAsync_connect(MQTTAsync handle, const MQTTAsync_connectOptions* options)
 		m->connect.onFailure5 = options->onFailure5;
 	}
 	m->connect.context = options->context;
-	m->connectTimeout = options->connectTimeout;
+	m->connectTimeoutMs = options->connectTimeout * 1000;
 
 	/* don't lock async mutex if we are being called from a callback */
 	thread_id = Paho_thread_getid();
@@ -679,8 +679,27 @@ int MQTTAsync_connect(MQTTAsync handle, const MQTTAsync_connectOptions* options)
 	if (options->struct_version >= 4)
 	{
 		m->automaticReconnect = options->automaticReconnect;
-		m->minRetryInterval = options->minRetryInterval;
-		m->maxRetryInterval = options->maxRetryInterval;
+		// Old retry time params were in seconds, but we want to support
+		// millisecond min retry intervals.
+		// To remain backwards compatible, if the param is under 100, we
+		// assume it's in seconds, otherwise, milliseconds.
+		if (options->minRetryInterval < 100)
+		{
+			m->minRetryIntervalMs = options->minRetryInterval * 1000;
+		}
+		else
+		{
+			m->minRetryIntervalMs = options->minRetryInterval;
+		}
+		// Similar for max interval, if it's under 1000, we assume seconds
+		if (options->maxRetryInterval < 1000)
+		{
+			m->maxRetryIntervalMs = options->maxRetryInterval * 1000;
+		}
+		else
+		{
+			m->maxRetryIntervalMs = options->maxRetryInterval;
+		}
 	}
 	if (options->struct_version >= 7)
 	{
@@ -847,7 +866,7 @@ int MQTTAsync_connect(MQTTAsync handle, const MQTTAsync_connectOptions* options)
 	m->c->retryInterval = options->retryInterval;
 	m->shouldBeConnected = 1;
 
-	m->connectTimeout = options->connectTimeout;
+	m->connectTimeoutMs = options->connectTimeout * 1000;
 
 	MQTTAsync_freeServerURIs(m);
 	if (options->struct_version >= 2 && options->serverURIcount > 0)
@@ -949,8 +968,8 @@ int MQTTAsync_reconnect(MQTTAsync handle)
 		if (m->shouldBeConnected)
 		{
 			m->reconnectNow = 1;
-			m->currentIntervalBase = m->minRetryInterval;
-			m->currentInterval = m->minRetryInterval;
+			m->currentIntervalBaseMs = m->minRetryIntervalMs;
+			m->currentIntervalMs = m->minRetryIntervalMs;
 			m->retrying = 1;
 			rc = MQTTASYNC_SUCCESS;
 		}
diff --git a/src/MQTTAsync.h b/src/MQTTAsync.h
index e11af0482..39bfc1a39 100644
--- a/src/MQTTAsync.h
+++ b/src/MQTTAsync.h
@@ -1267,6 +1267,9 @@ typedef struct
 	const char* password;
 	/**
       * The time interval in seconds to allow a connect to complete.
+      * The time interval in milliseconds to allow a connect to complete.
+      * For backwards compatibility and consistency with the retry intervals
+      * this is considered to be seconds if it is under 1000.
       */
 	int connectTimeout;
 	/**
@@ -1324,15 +1327,25 @@ typedef struct
 	  */
 	int MQTTVersion;
 	/**
-	  * Reconnect automatically in the case of a connection being lost. 0=false, 1=true
+	  * Reconnect automatically in the case of a connection being lost?
+	  * This retries with exponential backoff starting from the minRetryInterval
+	  * up to the maxRetryInterval, +/- 20% random jitter.
 	  */
 	int automaticReconnect;
 	/**
-	  * The minimum automatic reconnect retry interval in seconds. Doubled on each failed retry.
+	  * Minimum retry interval in milliseconds.  Doubled on each failed retry.
+	  * For backwards compatibility, if the value is under 100,
+	  * it is assumed to be in seconds rather than milliseconds.
+	  * Random jitter is applied to the value with +/- 20%
 	  */
 	int minRetryInterval;
 	/**
-	  * The maximum automatic reconnect retry interval in seconds. The doubling stops here on failed retries.
+	  * Maximum retry interval in milliseconds.  The doubling stops here on failed retries.
+	  * For backwards compatibility, if the value is under 1000,
+	  * it is assumed to be in seconds rather than milliseconds.
+	  * Note: due to random jitter, the actual max time interval could be as much as 20% higher,
+	  * but this will change on each retry.
+	  * e.g. for maxRetryInterval of 60 seconds, the actual wait time could be anywhere from 48 to 72 seconds
 	  */
 	int maxRetryInterval;
 	/**
diff --git a/src/MQTTAsyncUtils.c b/src/MQTTAsyncUtils.c
index 6d9330403..245b5294d 100644
--- a/src/MQTTAsyncUtils.c
+++ b/src/MQTTAsyncUtils.c
@@ -923,14 +923,14 @@ void MQTTAsync_startConnectRetry(MQTTAsyncs* m)
 		m->lastConnectionFailedTime = MQTTTime_start_clock();
 		if (m->retrying)
 		{
-			m->currentIntervalBase = min(m->currentIntervalBase * 2, m->maxRetryInterval);
+			m->currentIntervalBaseMs = min(m->currentIntervalBaseMs * 2, m->maxRetryIntervalMs);
 		}
 		else
 		{
-			m->currentIntervalBase = m->minRetryInterval;
+			m->currentIntervalBaseMs = m->minRetryIntervalMs;
 			m->retrying = 1;
 		}
-		m->currentInterval = MQTTAsync_randomJitter(m->currentIntervalBase, m->minRetryInterval, m->maxRetryInterval);
+		m->currentIntervalMs = MQTTAsync_randomJitter(m->currentIntervalBaseMs, m->minRetryIntervalMs, m->maxRetryIntervalMs);
 	}
 }
 
@@ -1701,7 +1701,7 @@ static void MQTTAsync_checkTimeouts(void)
 			MQTTAsync_checkDisconnect(m, &m->disconnect);
 
 		/* check connect timeout */
-		if (m->c->connect_state != NOT_IN_PROGRESS && MQTTTime_elapsed(m->connect.start_time) > (ELAPSED_TIME_TYPE)(m->connectTimeout * 1000))
+		if (m->c->connect_state != NOT_IN_PROGRESS && MQTTTime_elapsed(m->connect.start_time) > (ELAPSED_TIME_TYPE)(m->connectTimeoutMs))
 		{
 			nextOrClose(m, MQTTASYNC_FAILURE, "TCP connect timeout");
 			continue;
@@ -1715,7 +1715,7 @@ static void MQTTAsync_checkTimeouts(void)
 
 		if (m->automaticReconnect && m->retrying)
 		{
-			if (m->reconnectNow || MQTTTime_elapsed(m->lastConnectionFailedTime) > (ELAPSED_TIME_TYPE)(m->currentInterval * 1000))
+			if (m->reconnectNow || MQTTTime_elapsed(m->lastConnectionFailedTime) > (ELAPSED_TIME_TYPE)(m->currentIntervalMs))
 			{
 				/* to reconnect put the connect command to the head of the command queue */
 				MQTTAsync_queuedCommand* conn = malloc(sizeof(MQTTAsync_queuedCommand));
diff --git a/src/MQTTAsyncUtils.h b/src/MQTTAsyncUtils.h
index 0e08beac1..72576d1a1 100644
--- a/src/MQTTAsyncUtils.h
+++ b/src/MQTTAsyncUtils.h
@@ -126,16 +126,16 @@ typedef struct MQTTAsync_struct
 	int shouldBeConnected;
 	int noBufferedMessages; /* the current number of buffered (publish) messages for this client */
 
-	/* added for automatic reconnect */
+	/* added for automatic reconnect, intervals are in MS */
 	int automaticReconnect;
-	int minRetryInterval;
-	int maxRetryInterval;
+	int minRetryIntervalMs;
+	int maxRetryIntervalMs;
 	int serverURIcount;
 	char** serverURIs;
-	int connectTimeout;
+	int connectTimeoutMs;
 
-	int currentInterval;
-	int currentIntervalBase;
+	int currentIntervalMs;
+	int currentIntervalBaseMs;
 	START_TIME_TYPE lastConnectionFailedTime;
 	int retrying;
 	int reconnectNow;