diff --git a/makefile b/makefile
index ff4de6b9ec..8a2ea85182 100644
--- a/makefile
+++ b/makefile
@@ -54,6 +54,18 @@ test-executable = $(executable)
 boot-classpath = $(classpath-build)
 embed-prefix = /avian-embedded
 
+native-path = echo
+
+ifeq ($(build-platform),cygwin)
+	native-path = cygpath -m
+endif
+
+path-separator = :
+
+ifneq (,$(filter mingw32 cygwin,$(build-platform)))
+	path-separator = ;
+endif
+
 ifdef openjdk
 	ifdef openjdk-src
 		include openjdk-src.mk
@@ -72,11 +84,11 @@ ifdef openjdk
 	  options := $(options)-openjdk
 		test-executable = $(executable-dynamic)
 		library-path = LD_LIBRARY_PATH=$(build)
-		javahome = $(openjdk)/jre
+		javahome = "$$($(native-path) "$(openjdk)/jre")"
 	endif
 
   classpath = openjdk
-	boot-classpath := $(boot-classpath):$(openjdk)/jre/lib/rt.jar
+	boot-classpath := "$(boot-classpath)$(path-separator)$$($(native-path) "$(openjdk)/jre/lib/rt.jar")"
 	build-javahome = $(openjdk)/jre
 endif
 
@@ -127,7 +139,7 @@ warnings = -Wall -Wextra -Werror -Wunused-parameter -Winit-self \
 common-cflags = $(warnings) -fno-rtti -fno-exceptions -fno-omit-frame-pointer \
 	"-I$(JAVA_HOME)/include" -idirafter $(src) -I$(build) $(classpath-cflags) \
 	-D__STDC_LIMIT_MACROS -D_JNI_IMPLEMENTATION_ -DAVIAN_VERSION=\"$(version)\" \
-	-DUSE_ATOMIC_OPERATIONS "-DAVIAN_JAVA_HOME=\"$(javahome)\"" \
+	-DUSE_ATOMIC_OPERATIONS -DAVIAN_JAVA_HOME=\"$(javahome)\" \
 	-DAVIAN_EMBED_PREFIX=\"$(embed-prefix)\"
 
 build-cflags = $(common-cflags) -fPIC -fvisibility=hidden \
@@ -157,8 +169,6 @@ so-suffix = .so
 
 shared = -shared
 
-native-path = echo
-
 ifeq ($(arch),i386)
 	pointer-size = 4
 endif
@@ -241,7 +251,6 @@ ifeq ($(platform),windows)
 			build-cflags += -mno-cygwin
 			lflags += -mno-cygwin
 			cflags += -mno-cygwin
-			native-path = cygpath -m
 		endif
 	endif
 
diff --git a/src/classpath-openjdk.cpp b/src/classpath-openjdk.cpp
index a27c4ac9f4..13cab76928 100644
--- a/src/classpath-openjdk.cpp
+++ b/src/classpath-openjdk.cpp
@@ -1528,11 +1528,11 @@ Avian_sun_misc_Unsafe_compareAndSwapInt
 {
   object target = reinterpret_cast<object>(arguments[1]);
   int64_t offset; memcpy(&offset, arguments + 2, 8);
-  int32_t expect = arguments[4];
-  int32_t update = arguments[5];
+  uint32_t expect = arguments[4];
+  uint32_t update = arguments[5];
 
-  return __sync_bool_compare_and_swap
-    (&cast<int32_t>(target, offset), expect, update);
+  return atomicCompareAndSwap32
+    (&cast<uint32_t>(target, offset), expect, update);
 }
 
 extern "C" JNIEXPORT int64_t JNICALL
@@ -1541,11 +1541,11 @@ Avian_sun_misc_Unsafe_compareAndSwapObject
 {
   object target = reinterpret_cast<object>(arguments[1]);
   int64_t offset; memcpy(&offset, arguments + 2, 8);
-  intptr_t expect = arguments[4];
-  intptr_t update = arguments[5];
+  uintptr_t expect = arguments[4];
+  uintptr_t update = arguments[5];
 
-  bool success = __sync_bool_compare_and_swap
-    (&cast<intptr_t>(target, offset), expect, update);
+  bool success = atomicCompareAndSwap
+    (&cast<uintptr_t>(target, offset), expect, update);
 
   if (success) {
     mark(t, target, offset);
@@ -1560,11 +1560,11 @@ Avian_sun_misc_Unsafe_compareAndSwapLong
 {
   object target = reinterpret_cast<object>(arguments[1]);
   int64_t offset; memcpy(&offset, arguments + 2, 8);
-  int64_t expect; memcpy(&expect, arguments + 4, 8);
-  int64_t update; memcpy(&update, arguments + 6, 8);
+  uint64_t expect; memcpy(&expect, arguments + 4, 8);
+  uint64_t update; memcpy(&update, arguments + 6, 8);
 
-  return __sync_bool_compare_and_swap
-    (&cast<int64_t>(target, offset), expect, update);
+  return atomicCompareAndSwap64
+    (&cast<uint64_t>(target, offset), expect, update);
 }
 
 extern "C" JNIEXPORT int64_t JNICALL
diff --git a/src/x86.h b/src/x86.h
index 93278cdd7d..f5602b8015 100644
--- a/src/x86.h
+++ b/src/x86.h
@@ -223,6 +223,19 @@ atomicCompareAndSwap64(uint64_t* p, uint64_t old, uint64_t new_)
     (reinterpret_cast<LONGLONG*>(p), new_, old);
 #elif (__GNUC__ >= 4) && (__GNUC_MINOR__ >= 1)
   return __sync_bool_compare_and_swap(p, old, new_);
+#elif defined ARCH_x86_32
+  uint8_t result;
+
+  __asm__ __volatile__("lock; cmpxchg8b %0; setz %1"
+                       : "=m"(*p), "=q"(result)
+                       : "a"(static_cast<uint32_t>(old)),
+                         "d"(static_cast<uint32_t>(old >> 32)),
+                         "b"(static_cast<uint32_t>(new_)),
+                         "c"(static_cast<uint32_t>(new_ >> 32)),
+                         "m"(*p)
+                       : "memory");
+
+  return result != 0;
 #else
   uint8_t result;