diff --git a/icu4c/source/i18n/coll.cpp b/icu4c/source/i18n/coll.cpp
index 8cac0e5ebb..0f6f929f83 100644
--- a/icu4c/source/i18n/coll.cpp
+++ b/icu4c/source/i18n/coll.cpp
@@ -45,7 +45,7 @@
 #include "unicode/tblcoll.h"
 #include "ucol_imp.h"
 #include "cmemory.h"
-#include "mutex.h"
+#include "umutex.h"
 #include "servloc.h"
 #include "ustrenum.h"
 #include "ucln_in.h"
@@ -184,18 +184,16 @@ static ICULocaleService*
 getService(void)
 {
     UBool needInit;
-    {
-        Mutex mutex;
-        needInit = (UBool)(gService == NULL);
-    }
+    UMTX_CHECK(NULL, (UBool)(gService == NULL), needInit);
     if(needInit) {
         ICULocaleService *newservice = new ICUCollatorService();
         if(newservice) {
-            Mutex mutex;
+            umtx_lock(NULL);
             if(gService == NULL) {
                 gService = newservice;
                 newservice = NULL;
             }
+            umtx_unlock(NULL);
         }
         if(newservice) {
             delete newservice;
@@ -211,11 +209,12 @@ getService(void)
 
 // -------------------------------------
 
-static UBool
+static inline UBool
 hasService(void) 
 {
-    Mutex mutex;
-    return gService != NULL;
+    UBool retVal;
+    UMTX_CHECK(NULL, gService != NULL, retVal);
+    return retVal;
 }
 
 // -------------------------------------
diff --git a/icu4c/source/i18n/timezone.cpp b/icu4c/source/i18n/timezone.cpp
index 2952deb8e4..2c407586b0 100644
--- a/icu4c/source/i18n/timezone.cpp
+++ b/icu4c/source/i18n/timezone.cpp
@@ -362,13 +362,18 @@ static UBool loadOlsonIDs() {
 const TimeZone* U_EXPORT2
 TimeZone::getGMT(void)
 {
-    umtx_init(&LOCK);   /* This is here to prevent race conditions. */
-    Mutex lock(&LOCK);
+    UBool needsInit;
+    UMTX_CHECK(&LOCK, (_GMT == NULL), needsInit);   /* This is here to prevent race conditions. */
+
     // Initialize _GMT independently of other static data; it should
     // be valid even if we can't load the time zone UDataMemory.
-    if (_GMT == 0) {
-        _GMT = new SimpleTimeZone(0, UnicodeString(GMT_ID, GMT_ID_LENGTH));
-        ucln_i18n_registerCleanup(UCLN_I18N_TIMEZONE, timeZone_cleanup);
+    if (needsInit) {
+        umtx_lock(&LOCK);
+        if (_GMT == 0) {
+            _GMT = new SimpleTimeZone(0, UnicodeString(TRUE, GMT_ID, GMT_ID_LENGTH));
+            ucln_i18n_registerCleanup(UCLN_I18N_TIMEZONE, timeZone_cleanup);
+        }
+        umtx_unlock(&LOCK);
     }
     return _GMT;
 }
@@ -506,7 +511,7 @@ TimeZone::initDefault()
         // Some of the locale/timezone OS functions may not be thread safe, 
         //  so the intent is that any setting from anywhere within ICU 
         //  happens with the ICU global mutex held.
-        Mutex lock; 
+        Mutex lock;
         uprv_tzset(); // Initialize tz... system data
         
         // Get the timezone ID from the host.  This function should do