diff --git a/runtime/gc/heap.c b/runtime/gc/heap.c
index af1d9f8bb..668315d51 100644
--- a/runtime/gc/heap.c
+++ b/runtime/gc/heap.c
@@ -183,7 +183,9 @@ void shrinkHeap (GC_state s, GC_heap h, size_t keepSize) {
     }
     assert (isAligned (keepWithMapsSize, s->sysvals.pageSize));
     assert (keepWithMapsSize <= h->withMapsSize);
+#if HAS_SHRINK_HEAP
     GC_release (h->start + keepWithMapsSize, h->withMapsSize - keepWithMapsSize);
+#endif
     h->size = keepSize;
     h->withMapsSize = keepWithMapsSize;
   }
diff --git a/runtime/platform.h b/runtime/platform.h
index 6c3a44cfd..c88ea3b85 100644
--- a/runtime/platform.h
+++ b/runtime/platform.h
@@ -35,6 +35,10 @@
 #error HAS_REMAP not defined
 #endif
 
+#ifndef HAS_SHRINK_HEAP
+#error HAS_SHRINK_HEAP not defined
+#endif
+
 #ifndef HAS_SIGALTSTACK
 #error HAS_SIGALTSTACK not defined
 #else
diff --git a/runtime/platform/aix.h b/runtime/platform/aix.h
index 4869551f3..f7bb19037 100644
--- a/runtime/platform/aix.h
+++ b/runtime/platform/aix.h
@@ -34,6 +34,7 @@
 #define HAS_MSG_DONTWAIT FALSE
 #define HAS_PTRACE FALSE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/cygwin.h b/runtime/platform/cygwin.h
index 644fec5aa..29a0e7bae 100644
--- a/runtime/platform/cygwin.h
+++ b/runtime/platform/cygwin.h
@@ -35,6 +35,7 @@
 
 #define HAS_FEROUND FALSE
 #define HAS_REMAP TRUE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK FALSE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN TRUE
diff --git a/runtime/platform/darwin.h b/runtime/platform/darwin.h
index e5af03e32..ac2a0d936 100644
--- a/runtime/platform/darwin.h
+++ b/runtime/platform/darwin.h
@@ -34,6 +34,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/freebsd.h b/runtime/platform/freebsd.h
index 85d685df0..919127ec1 100644
--- a/runtime/platform/freebsd.h
+++ b/runtime/platform/freebsd.h
@@ -30,6 +30,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/hpux.h b/runtime/platform/hpux.h
index 62d83b649..aa8de42de 100644
--- a/runtime/platform/hpux.h
+++ b/runtime/platform/hpux.h
@@ -52,6 +52,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT FALSE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/hurd.h b/runtime/platform/hurd.h
index 7dbc46d5c..68fc44e88 100644
--- a/runtime/platform/hurd.h
+++ b/runtime/platform/hurd.h
@@ -30,6 +30,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP TRUE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/linux.h b/runtime/platform/linux.h
index 3f1ce7a60..423f9e11b 100644
--- a/runtime/platform/linux.h
+++ b/runtime/platform/linux.h
@@ -38,6 +38,7 @@
 #endif
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP TRUE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #if (defined (__hppa__))
 #define NEEDS_SIGALTSTACK_EXEC TRUE
diff --git a/runtime/platform/mingw.h b/runtime/platform/mingw.h
index f99352eb0..7441ee5e2 100644
--- a/runtime/platform/mingw.h
+++ b/runtime/platform/mingw.h
@@ -33,6 +33,7 @@
 #define HAS_FEROUND FALSE
 #define HAS_MSG_DONTWAIT FALSE
 #define HAS_REMAP TRUE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK FALSE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN TRUE
diff --git a/runtime/platform/netbsd.h b/runtime/platform/netbsd.h
index d2aef2e84..6bea1a501 100644
--- a/runtime/platform/netbsd.h
+++ b/runtime/platform/netbsd.h
@@ -30,6 +30,7 @@
 #define HAS_FEROUND FALSE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/openbsd.h b/runtime/platform/openbsd.h
index c6ca591e6..ffb816e0c 100644
--- a/runtime/platform/openbsd.h
+++ b/runtime/platform/openbsd.h
@@ -30,6 +30,7 @@
 #define HAS_FEROUND FALSE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/solaris.h b/runtime/platform/solaris.h
index 456d7fc7e..b752f3454 100644
--- a/runtime/platform/solaris.h
+++ b/runtime/platform/solaris.h
@@ -34,6 +34,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP TRUE
 #define HAS_SIGALTSTACK TRUE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE
diff --git a/runtime/platform/wasi.h b/runtime/platform/wasi.h
index 6b046d2e3..e978246bf 100644
--- a/runtime/platform/wasi.h
+++ b/runtime/platform/wasi.h
@@ -20,6 +20,7 @@
 #define HAS_FEROUND TRUE
 #define HAS_MSG_DONTWAIT TRUE
 #define HAS_REMAP FALSE
+#define HAS_SHRINK_HEAP FALSE
 #define HAS_SIGALTSTACK FALSE
 #define NEEDS_SIGALTSTACK_EXEC FALSE
 #define HAS_SPAWN FALSE