diff --git a/babel/dates.py b/babel/dates.py
index 69610a7f0..27b4eba08 100644
--- a/babel/dates.py
+++ b/babel/dates.py
@@ -461,18 +461,19 @@ def get_timezone_gmt(
 
     offset = datetime.tzinfo.utcoffset(datetime)
     seconds = offset.days * 24 * 60 * 60 + offset.seconds
-    hours, seconds = divmod(seconds, 3600)
+    sign = '-' if seconds < 0 else '+'
+    hours, seconds = divmod(abs(seconds), 3600)
     if return_z and hours == 0 and seconds == 0:
         return 'Z'
     elif seconds == 0 and width == 'iso8601_short':
-        return '%+03d' % hours
+        return '%s%02d' % (sign, hours)
     elif width == 'short' or width == 'iso8601_short':
-        pattern = '%+03d%02d'
+        pattern = '%s%02d%02d'
     elif width == 'iso8601':
-        pattern = '%+03d:%02d'
+        pattern = '%s%02d:%02d'
     else:
-        pattern = locale.zone_formats['gmt'] % '%+03d:%02d'
-    return pattern % (hours, seconds // 60)
+        pattern = locale.zone_formats['gmt'] % '%s%02d:%02d'
+    return pattern % (sign, hours, seconds // 60)
 
 
 def get_timezone_location(
diff --git a/tests/test_dates.py b/tests/test_dates.py
index 12bb23433..0ba18115a 100644
--- a/tests/test_dates.py
+++ b/tests/test_dates.py
@@ -455,6 +455,13 @@ def test_get_timezone_gmt(timezone_getter):
     assert dates.get_timezone_gmt(dt, 'short', locale='en') == '-0700'
     assert dates.get_timezone_gmt(dt, locale='en', width='iso8601_short') == '-07'
     assert dates.get_timezone_gmt(dt, 'long', locale='fr_FR') == 'UTC-07:00'
+    # A negative offset with a non-zero minute part must keep the correct hour
+    # (Newfoundland Standard Time is UTC-03:30, not UTC-04:30).
+    tz = timezone_getter('America/St_Johns')
+    dt = _localize(tz, datetime(2007, 1, 1, 12, 0))
+    assert dates.get_timezone_gmt(dt, locale='en') == 'GMT-03:30'
+    assert dates.get_timezone_gmt(dt, 'short', locale='en') == '-0330'
+    assert dates.get_timezone_gmt(dt, locale='en', width='iso8601') == '-03:30'
 
 
 def test_get_timezone_location(timezone_getter):