diff --git a/src/pkg/runtime/error.go b/src/pkg/runtime/error.go
index b6b520cf27..bd70908839 100644
--- a/src/pkg/runtime/error.go
+++ b/src/pkg/runtime/error.go
@@ -74,6 +74,22 @@ func newErrorString(s string, ret *interface{}) {
 	*ret = errorString(s)
 }
 
+// An errorCString represents a runtime error described by a single C string.
+type errorCString uintptr
+
+func (e errorCString) RuntimeError() {}
+
+func cstringToGo(uintptr) string
+
+func (e errorCString) Error() string {
+	return "runtime error: " + cstringToGo(uintptr(e))
+}
+
+// For calling from C.
+func newErrorCString(s uintptr, ret *interface{}) {
+	*ret = errorCString(s)
+}
+
 type stringer interface {
 	String() string
 }
diff --git a/src/pkg/runtime/panic.c b/src/pkg/runtime/panic.c
index a1e91d3d8f..8227a444d3 100644
--- a/src/pkg/runtime/panic.c
+++ b/src/pkg/runtime/panic.c
@@ -470,11 +470,15 @@ runtime·panicstring(int8 *s)
 {
 	Eface err;
 
+	if(m->mallocing) {
+		runtime·printf("panic: %s\n", s);
+		runtime·throw("panic during malloc");
+	}
 	if(m->gcing) {
 		runtime·printf("panic: %s\n", s);
 		runtime·throw("panic during gc");
 	}
-	runtime·newErrorString(runtime·gostringnocopy((byte*)s), &err);
+	runtime·newErrorCString(s, &err);
 	runtime·panic(err);
 }
 
diff --git a/src/pkg/runtime/proc.c b/src/pkg/runtime/proc.c
index e34e9e5067..d5fc2dcac5 100644
--- a/src/pkg/runtime/proc.c
+++ b/src/pkg/runtime/proc.c
@@ -128,6 +128,7 @@ runtime·schedinit(void)
 {
 	int32 n, procs;
 	byte *p;
+	Eface i;
 
 	runtime·sched.maxmcount = 10000;
 	runtime·precisestack = haveexperiment("precisestack");
@@ -136,6 +137,12 @@ runtime·schedinit(void)
 	runtime·mprofinit();
 	runtime·mallocinit();
 	mcommoninit(m);
+	
+	// Initialize the itable value for newErrorCString,
+	// so that the next time it gets called, possibly
+	// in a fault during a garbage collection, it will not
+	// need to allocated memory.
+	runtime·newErrorCString(0, &i);
 
 	runtime·goargs();
 	runtime·goenvs();
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 66e87d5c27..c989edcf8d 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -1004,6 +1004,7 @@ void	runtime·panicslice(void);
 void	runtime·printany(Eface);
 void	runtime·newTypeAssertionError(String*, String*, String*, String*, Eface*);
 void	runtime·newErrorString(String, Eface*);
+void	runtime·newErrorCString(int8*, Eface*);
 void	runtime·fadd64c(uint64, uint64, uint64*);
 void	runtime·fsub64c(uint64, uint64, uint64*);
 void	runtime·fmul64c(uint64, uint64, uint64*);
diff --git a/src/pkg/runtime/string.goc b/src/pkg/runtime/string.goc
index 5d472208bf..b79acbe1c2 100644
--- a/src/pkg/runtime/string.goc
+++ b/src/pkg/runtime/string.goc
@@ -102,6 +102,13 @@ runtime·gostringnocopy(byte *str)
 	return s;
 }
 
+void
+runtime·cstringToGo(byte *str, String s)
+{
+	s = runtime·gostringnocopy(str);
+	FLUSH(&s);
+}
+
 String
 runtime·gostringw(uint16 *str)
 {