diff --git a/coregrind/Makefile.am b/coregrind/Makefile.am
index 596d28434..0f3a3dfe1 100644
--- a/coregrind/Makefile.am
+++ b/coregrind/Makefile.am
@@ -52,9 +52,9 @@ valgrind_LDFLAGS=-static -g
 valgrind_LDADD=
 
 stage2_SOURCES = \
-	errormgr.c \
-	execontext.c \
-	stacktrace.c \
+	m_errormgr.c \
+	m_execontext.c \
+	m_stacktrace.c \
 	ume.c \
 	\
 	vg_scheduler.c \
diff --git a/coregrind/errormgr.c b/coregrind/m_errormgr.c
similarity index 99%
rename from coregrind/errormgr.c
rename to coregrind/m_errormgr.c
index fa61362d0..fc10a3de2 100644
--- a/coregrind/errormgr.c
+++ b/coregrind/m_errormgr.c
@@ -1,6 +1,6 @@
 
 /*--------------------------------------------------------------------*/
-/*--- Management of error messages.                     errormgr.c ---*/
+/*--- Management of error messages.                   m_errormgr.c ---*/
 /*--------------------------------------------------------------------*/
 
 /*
@@ -1027,5 +1027,5 @@ static Supp* is_suppressible_error ( Error* err )
 }
 
 /*--------------------------------------------------------------------*/
-/*--- end                                                          ---*/
+/*--- end                                             m_errormgr.c ---*/
 /*--------------------------------------------------------------------*/
diff --git a/coregrind/execontext.c b/coregrind/m_execontext.c
similarity index 98%
rename from coregrind/execontext.c
rename to coregrind/m_execontext.c
index 5de1dbe92..59ea65c77 100644
--- a/coregrind/execontext.c
+++ b/coregrind/m_execontext.c
@@ -1,5 +1,6 @@
+
 /*--------------------------------------------------------------------*/
-/*---                                                 execontext.c ---*/
+/*--- Store and compare stack backtraces            m_execontext.c ---*/
 /*--------------------------------------------------------------------*/
 
 /*
@@ -252,5 +253,5 @@ StackTrace VG_(extract_StackTrace) ( ExeContext* e )
 }  
 
 /*--------------------------------------------------------------------*/
-/*--- end                                                          ---*/
+/*--- end                                           m_execontext.c ---*/
 /*--------------------------------------------------------------------*/
diff --git a/coregrind/stacktrace.c b/coregrind/m_stacktrace.c
similarity index 98%
rename from coregrind/stacktrace.c
rename to coregrind/m_stacktrace.c
index 5821d584d..d43168ee8 100644
--- a/coregrind/stacktrace.c
+++ b/coregrind/m_stacktrace.c
@@ -1,5 +1,6 @@
+
 /*--------------------------------------------------------------------*/
-/*---                                                 stacktrace.c ---*/
+/*--- Take snapshots of client stacks.              m_stacktrace.c ---*/
 /*--------------------------------------------------------------------*/
 
 /*
@@ -200,5 +201,5 @@ void VG_(apply_StackTrace)( void(*action)(UInt n, Addr ip),
 
 
 /*--------------------------------------------------------------------*/
-/*--- end                                                          ---*/
+/*--- end                                           m_stacktrace.c ---*/
 /*--------------------------------------------------------------------*/