diff --git a/Makefile.in b/Makefile.in
index 1b4eb6ba4f..ac8652ea1d 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -213,7 +213,7 @@ DTRACE_REBUILD= @DTRACE_REBUILD@
 DTRACE_GLOMMED_OBJ = $(DTRACE_REBUILD:yes=ruby-glommed.$(OBJEXT))
 
 OBJEXT        = @OBJEXT@
-ASMEXT        = s
+ASMEXT        = S
 SOEXT         = @SOEXT@
 DLEXT         = @DLEXT@
 MANTYPE	      = @MANTYPE@
diff --git a/coroutine/amd64/Context.s b/coroutine/amd64/Context.S
similarity index 100%
rename from coroutine/amd64/Context.s
rename to coroutine/amd64/Context.S
diff --git a/coroutine/arm32/Context.s b/coroutine/arm32/Context.S
similarity index 100%
rename from coroutine/arm32/Context.s
rename to coroutine/arm32/Context.S
diff --git a/coroutine/arm64/Context.s b/coroutine/arm64/Context.S
similarity index 100%
rename from coroutine/arm64/Context.s
rename to coroutine/arm64/Context.S
diff --git a/coroutine/win64/Context.s b/coroutine/win64/Context.S
similarity index 100%
rename from coroutine/win64/Context.s
rename to coroutine/win64/Context.S
diff --git a/coroutine/x86/Context.s b/coroutine/x86/Context.S
similarity index 100%
rename from coroutine/x86/Context.s
rename to coroutine/x86/Context.S
diff --git a/ia64.s b/ia64.S
similarity index 100%
rename from ia64.s
rename to ia64.S