diff --git a/Makefile.system b/Makefile.system
index da6a6a560..7da074a65 100644
--- a/Makefile.system
+++ b/Makefile.system
@@ -229,6 +229,11 @@ endif
 endif
 endif
 
+# ifeq logical or
+ifeq ($(OSNAME), $(filter $(OSNAME),WINNT CYGWIN_NT Interix))
+OS_WINDOWS=1
+endif
+
 ifdef QUAD_PRECISION
 CCOMMON_OPT	+= -DQUAD_PRECISION
 NO_EXPRECISION = 1
@@ -849,6 +854,9 @@ LAPACK_CFLAGS += -DHAVE_LAPACK_CONFIG_H
 ifdef INTERFACE64
 LAPACK_CFLAGS +=  -DLAPACK_ILP64
 endif
+ifdef OS_WINDOWS
+LAPACK_CFLAGS +=  -DOPENBLAS_OS_WINDOWS
+endif
 ifeq ($(C_COMPILER), LSB)
 LAPACK_CFLAGS +=  -DLAPACK_COMPLEX_STRUCTURE
 endif
diff --git a/driver/others/memory.c b/driver/others/memory.c
index 4f35691ff..35758d13c 100644
--- a/driver/others/memory.c
+++ b/driver/others/memory.c
@@ -363,7 +363,7 @@ static void *alloc_mmap(void *address){
 #define BENCH_ITERATION 4
 #define SCALING		2
 
-static inline BLASULONG run_bench(BLASULONG address, long size) {
+static inline BLASULONG run_bench(BLASULONG address, BLASULONG size) {
 
   BLASULONG original, *p;
   BLASULONG start, stop, min;
@@ -450,12 +450,12 @@ static void *alloc_mmap(void *address){
 	current = (SCALING - 1) * BUFFER_SIZE;
 	
 	while(current > 0) {
-	  *(long *)start = (long)start + PAGESIZE;
+	  *(BLASLONG *)start = (BLASLONG)start + PAGESIZE;
 	  start += PAGESIZE;
 	  current -= PAGESIZE;
 	}
 	
-	*(long *)(start - PAGESIZE) = (BLASULONG)map_address;
+	*(BLASLONG *)(start - PAGESIZE) = (BLASULONG)map_address;
 	
 	start = (BLASULONG)map_address;
 	
@@ -1170,7 +1170,7 @@ static void _touch_memory(blas_arg_t *arg, BLASLONG *range_m, BLASLONG *range_n,
 
 #if !defined(ARCH_POWER) && !defined(ARCH_SPARC)
 
-  long size;
+  size_t size;
   BLASULONG buffer;
 
   size   = BUFFER_SIZE - PAGESIZE;
diff --git a/lapack-netlib/lapacke/include/lapacke_config.h b/lapack-netlib/lapacke/include/lapacke_config.h
index 1e2509bf0..561b2736b 100644
--- a/lapack-netlib/lapacke/include/lapacke_config.h
+++ b/lapack-netlib/lapacke/include/lapacke_config.h
@@ -45,7 +45,11 @@ extern "C" {
 
 #ifndef lapack_int
 #if defined(LAPACK_ILP64)
+#if defined(OPENBLAS_OS_WINDOWS)
+#define lapack_int              long long
+#else
 #define lapack_int              long
+#endif
 #else
 #define lapack_int              int
 #endif
diff --git a/lapack/getrf/getrf_parallel.c b/lapack/getrf/getrf_parallel.c
index 21ea9d5f5..3dbc70e9d 100644
--- a/lapack/getrf/getrf_parallel.c
+++ b/lapack/getrf/getrf_parallel.c
@@ -67,14 +67,14 @@ double sqrt(double);
 #undef  GETRF_FACTOR
 #define GETRF_FACTOR 1.00
 
-static inline long FORMULA1(long M, long N, long IS, long BK, long T) {
+static inline BLASLONG FORMULA1(BLASLONG M, BLASLONG N, BLASLONG IS, BLASLONG BK, BLASLONG T) {
 
   double m = (double)(M - IS - BK);
   double n = (double)(N - IS - BK);
   double b = (double)BK;
   double a = (double)T;
 
-  return (long)((n + GETRF_FACTOR * m * b * (1. - a) / (b + m)) / a);
+  return (BLASLONG)((n + GETRF_FACTOR * m * b * (1. - a) / (b + m)) / a);
 
 }
 
@@ -111,7 +111,7 @@ static void inner_basic_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *ra
 
   if (args -> a == NULL) {
     TRSM_ILTCOPY(k, k, (FLOAT *)args -> b, lda, 0, sb);
-    sbb = (FLOAT *)((((long)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+    sbb = (FLOAT *)((((BLASULONG)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
   } else {
     sb  = (FLOAT *)args -> a;
   }
@@ -221,7 +221,7 @@ static int inner_advanced_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *
 
   if (args -> a == NULL) {
     TRSM_ILTCOPY(k, k, (FLOAT *)args -> b, lda, 0, sb);
-    sbb = (FLOAT *)((((long)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+    sbb = (FLOAT *)((((BLASULONG)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
   } else {
     sb  = (FLOAT *)args -> a;
   }
@@ -448,7 +448,7 @@ blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa,
 
   TRSM_ILTCOPY(bk, bk, a, lda, 0, sb);
 
-  sbb = (FLOAT *)((((long)(sb + bk * bk * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+  sbb = (FLOAT *)((((BLASULONG)(sb + bk * bk * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
   
   is = 0;
   num_cpu = 0;
@@ -685,7 +685,7 @@ blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa,
   if (width > n - init_bk) width = n - init_bk;
 
   if (width < init_bk) {
-    long temp;
+    BLASLONG temp;
 
     temp = FORMULA2(m, n, 0, init_bk, args -> nthreads);
     temp = (temp + GEMM_UNROLL_N - 1) & ~(GEMM_UNROLL_N - 1);
@@ -708,7 +708,7 @@ blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa,
   is = 0;
   num_cpu = 0;
 
-  sbb = (FLOAT *)((((long)(sb + GEMM_PQ * GEMM_PQ * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+  sbb = (FLOAT *)((((BLASULONG)(sb + GEMM_PQ * GEMM_PQ * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
 
   while (is < mn) {
 
diff --git a/lapack/getrf/getrf_parallel_omp.c b/lapack/getrf/getrf_parallel_omp.c
index 4922b9b52..6eda30a52 100644
--- a/lapack/getrf/getrf_parallel_omp.c
+++ b/lapack/getrf/getrf_parallel_omp.c
@@ -178,7 +178,7 @@ blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa,
     return info;
   }
   
-  sbb = (FLOAT *)((((long)(sb + blocking * blocking * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+  sbb = (FLOAT *)((((BLASULONG)(sb + blocking * blocking * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
 
   info = 0;
 
diff --git a/lapack/getrf/getrf_single.c b/lapack/getrf/getrf_single.c
index fcea0ae89..f1818ea97 100644
--- a/lapack/getrf/getrf_single.c
+++ b/lapack/getrf/getrf_single.c
@@ -82,7 +82,7 @@ blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa,
     return info;
   }
   
-  sbb = (FLOAT *)((((long)(sb + blocking * blocking * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+  sbb = (FLOAT *)((((BLASULONG)(sb + blocking * blocking * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
 
   info = 0;
 
diff --git a/lapack/potrf/potrf_parallel.c b/lapack/potrf/potrf_parallel.c
index eec9b6e05..11f7f533c 100644
--- a/lapack/potrf/potrf_parallel.c
+++ b/lapack/potrf/potrf_parallel.c
@@ -185,7 +185,7 @@ static int inner_thread(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n,
 
   div_n = ((m_to - m_from + DIVIDE_RATE - 1) / DIVIDE_RATE + GEMM_UNROLL_MN - 1) & ~(GEMM_UNROLL_MN - 1);
 
-  buffer[0] = (FLOAT *)((((long)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
+  buffer[0] = (FLOAT *)((((BLASULONG)(sb + k * k * COMPSIZE) + GEMM_ALIGN) & ~GEMM_ALIGN) + GEMM_OFFSET_B);
   for (i = 1; i < DIVIDE_RATE; i++) {
     buffer[i] = buffer[i - 1] + GEMM_Q * div_n * COMPSIZE;
   }