1 files changed, 14 insertions, 5 deletions

diff --git a/rts/win32/OSMem.c b/rts/win32/OSMem.c
index c62ee3b7a4..57997b1ac5 100644
--- a/rts/win32/OSMem.c
+++ b/rts/win32/OSMem.c
@@ -144,8 +144,11 @@ findFreeBlocks(uint32_t n) {
     temp.next=free_blocks; temp.base=0; temp.size=0;
     prev=&temp;
     /* TODO: Don't just take first block, find smallest sufficient block */
-    for( ; it!=0 && it->size<required_size; prev=it, it=it->next ) {}
-    if(it!=0) {
+    for ( ; it; prev=it, it=it->next )
+      {
+        if (!it || it->size < required_size)
+          continue;
+
         if( (((W_)it->base) & MBLOCK_MASK) == 0) { /* MBlock aligned */
             ret = (void*)it->base;
             if(it->size==required_size) {
@@ -155,24 +158,30 @@ findFreeBlocks(uint32_t n) {
                 it->base += required_size;
                 it->size -=required_size;
             }
+            break;
         } else {
             char* need_base;
             block_rec* next;
             int new_size;
             need_base =
                 (char*)(((W_)it->base) & ((W_)~MBLOCK_MASK)) + MBLOCK_SIZE;
+            new_size = need_base - it->base;
+            /* Make sure that after alignment we have enough space.  */
+            W_ total_size = new_size + required_size;
+            if (total_size > it->size)
+              continue;
             next = (block_rec*)stgMallocBytes(
                     sizeof(block_rec)
                     , "getMBlocks: findFreeBlocks: splitting");
-            new_size = need_base - it->base;
             next->base = need_base +required_size;
-            next->size = it->size - (new_size+required_size);
+            next->size = it->size - total_size;
             it->size = new_size;
             next->next = it->next;
             it->next = next;
             ret=(void*)need_base;
+            break;
         }
-    }
+      }
     free_blocks=temp.next;
     return ret;
 }