diff --git a/src/builtins.c b/src/builtins.c
index 31cdc992a8daa..007c05a3bac57 100644
--- a/src/builtins.c
+++ b/src/builtins.c
@@ -39,6 +39,8 @@ DLLEXPORT void NORETURN jl_error(const char *str)
     jl_throw(jl_new_struct(jl_errorexception_type, msg));
 }
 
+extern int vasprintf(char **str, const char *fmt, va_list ap);
+
 static void NORETURN jl_vexceptionf(jl_datatype_t *exception_type, const char *fmt, va_list args)
 {
     if (exception_type == NULL) {
diff --git a/src/codegen.cpp b/src/codegen.cpp
index 05ad117c8487a..5d7875ffb3ec5 100644
--- a/src/codegen.cpp
+++ b/src/codegen.cpp
@@ -160,6 +160,10 @@ extern void _chkstk(void);
 #endif
 }
 
+#if defined(_COMPILER_MICROSOFT_) && !defined(__alignof__)
+#define __alignof__ __alignof
+#endif
+
 #define DISABLE_FLOAT16
 
 // llvm state
@@ -791,7 +795,7 @@ static Function *jl_cfunction_object(jl_function_t *f, jl_value_t *rt, jl_value_
 
     uint64_t isref = 0; // bit vector of which argument types are a subtype of Type{Ref{T}}
     jl_value_t *sigt; // type signature with Ref{} annotations removed
-    JL_GC_PUSH(&sigt);
+    JL_GC_PUSH1(&sigt);
     sigt = (jl_value_t*)jl_alloc_tuple(nargs);
     for (i = 0; i < nargs; i++) {
         jl_value_t *ati = jl_tupleref(argt, i);
diff --git a/src/dump.c b/src/dump.c
index a15de669987d3..aca39b0b668cb 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -5,8 +5,6 @@
 #include <string.h>
 #include <assert.h>
 
-#include "valgrind.h"
-
 #include "julia.h"
 #include "julia_internal.h"
 #include "builtin_proto.h"
@@ -15,6 +13,12 @@
 #include <dlfcn.h>
 #endif
 
+#ifndef _COMPILER_MICROSOFT_
+#include "valgrind.h"
+#else
+#define RUNNING_ON_VALGRIND 0
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/src/jl_uv.c b/src/jl_uv.c
index 1ae7e5afd9494..0395d3a3b3602 100644
--- a/src/jl_uv.c
+++ b/src/jl_uv.c
@@ -29,6 +29,11 @@
 #include "support/ios.h"
 #include "uv.h"
 
+#if defined(_COMPILER_MICROSOFT_) && !defined(write)
+#include <io.h>
+#define write _write
+#endif
+
 #ifdef __cplusplus
 #include <cstring>
 extern "C" {
diff --git a/src/support/dtypes.h b/src/support/dtypes.h
index a09d517895775..9ccb64151dc46 100644
--- a/src/support/dtypes.h
+++ b/src/support/dtypes.h
@@ -37,10 +37,6 @@
 
 #endif /* !_COMPILER_MINGW_ */
 
-#if defined(_COMPILER_MICROSOFT_)
-#define isnan _isnan
-#endif /* _COMPILER_MICROSOFT_ */
-
 #endif /* _OS_WINDOWS_ */
 
 
diff --git a/src/task.c b/src/task.c
index 15de40c7d1c70..a3d592e22616e 100644
--- a/src/task.c
+++ b/src/task.c
@@ -152,7 +152,7 @@ jl_gcframe_t *jl_pgcstack = NULL;
 #ifdef COPY_STACKS
 static jl_jmp_buf * volatile jl_jmp_target;
 
-#if defined(_CPU_X86_64_) || defined(_CPU_X86_)
+#if (defined(_CPU_X86_64_) || defined(_CPU_X86_)) && !defined(_COMPILER_MICROSOFT_)
 #define ASM_COPY_STACKS
 #endif
 void *jl_stackbase;