diff --git a/libgc/alloc.c b/libgc/alloc.c
index 9ec6992352ad..b6bc1832c994 100644
--- a/libgc/alloc.c
+++ b/libgc/alloc.c
@@ -969,7 +969,7 @@ word n;
       }
 #   endif
     expansion_slop = WORDS_TO_BYTES(min_words_allocd()) + 4*MAXHINCR*HBLKSIZE;
-    if (GC_last_heap_addr == 0 && !((word)space & SIGNB)
+    if ((GC_last_heap_addr == 0 && !((word)space & SIGNB))
         || (GC_last_heap_addr != 0 && GC_last_heap_addr < (ptr_t)space)) {
         /* Assume the heap is growing up */
         GC_greatest_plausible_heap_addr =
diff --git a/libgc/obj_map.c b/libgc/obj_map.c
index 39993451cc71..49f6add1553d 100644
--- a/libgc/obj_map.c
+++ b/libgc/obj_map.c
@@ -22,7 +22,7 @@
 # include "private/gc_priv.h"
 
 map_entry_type * GC_invalid_map = 0;
-static max_valid_offset = 0;
+static word max_valid_offset = 0;
 
 /* Invalidate the object map associated with a block.	Free blocks	*/
 /* are identified by invalid maps.					*/
diff --git a/libgc/ptr_chck.c b/libgc/ptr_chck.c
index d83d730d3433..621a45f0346f 100644
--- a/libgc/ptr_chck.c
+++ b/libgc/ptr_chck.c
@@ -165,7 +165,7 @@ void (*GC_is_valid_displacement_print_proc) GC_PROTO((GC_PTR)) =
     pdispl = HBLKDISPL(p);
     map_entry = MAP_ENTRY((hhdr -> hb_map), pdispl);
     if (map_entry == OBJ_INVALID
-    	|| sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz) {
+    	|| (sz > MAXOBJBYTES && (ptr_t)p >= (ptr_t)h + sz)) {
     	goto fail;
     }
     return(p);