diff --git a/Makefile b/Makefile
index bb8688f8..39ac2eb8 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,8 @@ INCS ?= -Isrc -I.
 SSL ?= MBEDTLS
 CWD ?= $(realpath $(CURDIR))
 ENV ?=  -e Tmp=. -e WINEDEBUG=-all 
-DOCKER ?= docker run --platform linux/amd64 --rm $(ENV) -v $(CWD):$(CWD) -w $(CWD)
+DOCKERCMD ?= docker
+DOCKER ?= $(DOCKERCMD) run --rm $(ENV) -v $(CWD):$(CWD) -w $(CWD)
 VCFLAGS = /nologo /W3 /O2 /MD /I. $(DEFS) $(TFLAGS)
 IPV6 ?= 1
 ASAN ?= -fsanitize=address,undefined -fno-sanitize-recover=all
diff --git a/mongoose.c b/mongoose.c
index f062cc99..873ce1bd 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -3912,8 +3912,8 @@ void mg_sha1_final(unsigned char digest[20], mg_sha1_ctx *context) {
 
 
 
-#define SNTP_TIME_OFFSET 2208988800UL  // (1970 - 1900) in seconds
-#define SNTP_MAX_FRAC 4294967295.0     // 2 ** 32 - 1
+#define SNTP_TIME_OFFSET 2208988800U  // (1970 - 1900) in seconds
+#define SNTP_MAX_FRAC 4294967295.0    // 2 ** 32 - 1
 
 static int64_t gettimestamp(const uint32_t *data) {
   uint32_t sec = mg_ntohl(data[0]), frac = mg_ntohl(data[1]);
@@ -3970,9 +3970,10 @@ void mg_sntp_request(struct mg_connection *c) {
     uint64_t now = mg_millis();
     uint8_t buf[48] = {0};
     uint32_t *t = (uint32_t *) &buf[40];
+    double frac = ((double) (now % 1000)) / 1000.0;
     buf[0] = (0 << 6) | (4 << 3) | 3;
     t[0] = mg_htonl((uint32_t) (now / 1000) + SNTP_TIME_OFFSET);
-    t[1] = mg_htonl((uint32_t) ((now % 1000) / 1000.0 * SNTP_MAX_FRAC));
+    t[1] = mg_htonl((uint32_t) ((uint32_t) (frac * SNTP_MAX_FRAC)));
     mg_send(c, buf, sizeof(buf));
   }
 }
diff --git a/src/sntp.c b/src/sntp.c
index 9491ec1e..86bc4d6f 100644
--- a/src/sntp.c
+++ b/src/sntp.c
@@ -4,8 +4,8 @@
 #include "log.h"
 #include "util.h"
 
-#define SNTP_TIME_OFFSET 2208988800UL  // (1970 - 1900) in seconds
-#define SNTP_MAX_FRAC 4294967295.0     // 2 ** 32 - 1
+#define SNTP_TIME_OFFSET 2208988800U  // (1970 - 1900) in seconds
+#define SNTP_MAX_FRAC 4294967295.0    // 2 ** 32 - 1
 
 static int64_t gettimestamp(const uint32_t *data) {
   uint32_t sec = mg_ntohl(data[0]), frac = mg_ntohl(data[1]);
@@ -62,9 +62,10 @@ void mg_sntp_request(struct mg_connection *c) {
     uint64_t now = mg_millis();
     uint8_t buf[48] = {0};
     uint32_t *t = (uint32_t *) &buf[40];
+    double frac = ((double) (now % 1000)) / 1000.0;
     buf[0] = (0 << 6) | (4 << 3) | 3;
     t[0] = mg_htonl((uint32_t) (now / 1000) + SNTP_TIME_OFFSET);
-    t[1] = mg_htonl((uint32_t) ((now % 1000) / 1000.0 * SNTP_MAX_FRAC));
+    t[1] = mg_htonl((uint32_t) ((uint32_t) (frac * SNTP_MAX_FRAC)));
     mg_send(c, buf, sizeof(buf));
   }
 }