diff --git a/common/include/dxxerror.h b/common/include/dxxerror.h
index 3e8e22715..e24adda0b 100644
--- a/common/include/dxxerror.h
+++ b/common/include/dxxerror.h
@@ -39,6 +39,8 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #define __noreturn
 #endif
 
+inline namespace dcx {
+
 int error_init(void (*func)(const char *));    //init error system, returns 0=ok
 void Warning_puts(const char *str) __attribute_nonnull();
 void Warning(const char *fmt,...) __attribute_format_printf(1, 2);				//print out warning message to user
@@ -116,4 +118,6 @@ static inline void d_debugbreak()
 
 }
 
+}
+
 #endif
diff --git a/common/include/hash.h b/common/include/hash.h
index bde91b888..9b3946046 100644
--- a/common/include/hash.h
+++ b/common/include/hash.h
@@ -18,13 +18,12 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 */
 
 
+#pragma once
 
-#ifndef _HASH_H
-#define _HASH_H
-
-#ifdef __cplusplus
 #include <map>
 
+inline namespace dcx {
+
 struct hashtable
 {
 	struct compare_t
@@ -37,6 +36,4 @@ struct hashtable
 int hashtable_search( hashtable *ht, const char *key );
 void hashtable_insert( hashtable *ht, const char *key, int value );
 
-#endif
-
-#endif
+}
diff --git a/common/include/hmp.h b/common/include/hmp.h
index df4626f5f..178a32bef 100644
--- a/common/include/hmp.h
+++ b/common/include/hmp.h
@@ -16,6 +16,7 @@
 #include "physfsx.h"
 
 #ifdef __cplusplus
+inline namespace dcx {
 
 #define HMP_TRACKS 32
 #ifdef _WIN32
@@ -101,6 +102,7 @@ void hmp_resume(hmp_file *hmp);
 void hmp_reset();
 #endif
 
+}
 #endif
 
 #endif
diff --git a/common/include/ignorecase.h b/common/include/ignorecase.h
index e5b243108..e4b220674 100644
--- a/common/include/ignorecase.h
+++ b/common/include/ignorecase.h
@@ -54,6 +54,8 @@
 
 #ifdef __cplusplus
 
+inline namespace dcx {
+
 /**
  * \fn int PHYSFSEXT_locateCorrectCase(char *buf)
  * \brief Find an existing filename with matching case.
@@ -82,5 +84,7 @@ int PHYSFSEXT_locateCorrectCase(char *buf);
 
 /* end of ignorecase.h ... */
 
+}
+
 #endif
 
diff --git a/common/include/strutil.h b/common/include/strutil.h
index 69fe8a258..0f970c9a0 100644
--- a/common/include/strutil.h
+++ b/common/include/strutil.h
@@ -13,6 +13,8 @@
 #include "dxxsconf.h"
 #include <vector>
 
+inline namespace dcx {
+
 #if defined(macintosh)
 #define snprintf macintosh_snprintf
 extern void snprintf(char *out_string, int size, const char * format, ... );
@@ -80,4 +82,6 @@ public:
 
 int string_array_sort_func(char **e0, char **e1);
 
+}
+
 #endif
diff --git a/common/misc/error.cpp b/common/misc/error.cpp
index c5a2d5f9d..cfdb21689 100644
--- a/common/misc/error.cpp
+++ b/common/misc/error.cpp
@@ -31,6 +31,8 @@ COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include "console.h"
 #include "dxxerror.h"
 
+inline namespace dcx {
+
 #define MAX_MSG_LEN 2048
 
 static void (*ErrorPrintFunc)(const char *);
@@ -148,3 +150,5 @@ int error_init(void (*func)(const char *))
 	ErrorPrintFunc = func;          // Set Error Print Functions
 	return 0;
 }
+
+}
diff --git a/common/misc/hash.cpp b/common/misc/hash.cpp
index f7720e4ff..291111a46 100644
--- a/common/misc/hash.cpp
+++ b/common/misc/hash.cpp
@@ -25,6 +25,8 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 #include <string.h>
 #include "hash.h"
 
+inline namespace dcx {
+
 bool hashtable::compare_t::operator()(const char *l, const char *r) const
 {
 	for (;; ++l, ++r)
@@ -49,3 +51,5 @@ void hashtable_insert(hashtable *ht, const char *key, int value)
 {
 	ht->m.insert(std::make_pair(key, value));
 }
+
+}
diff --git a/common/misc/hmp.cpp b/common/misc/hmp.cpp
index 66f75eea9..552b27089 100644
--- a/common/misc/hmp.cpp
+++ b/common/misc/hmp.cpp
@@ -27,6 +27,8 @@
 #include "compiler-range_for.h"
 #include "partial_range.h"
 
+inline namespace dcx {
+
 #define MIDIINT(x)	(words_bigendian ? (x) : (SWAPINT(x)))
 #define MIDISHORT(x)	(words_bigendian ? (x) : (SWAPSHORT(x)))
 
@@ -712,3 +714,5 @@ void hmp2mid(const char *hmp_name, std::vector<uint8_t> &midbuf)
 		serial::process_buffer(bbmi, static_cast<int32_t>(size_after - size_before));
 	}
 }
+
+}
diff --git a/common/misc/ignorecase.cpp b/common/misc/ignorecase.cpp
index 4dd2294fb..9ad632bdf 100644
--- a/common/misc/ignorecase.cpp
+++ b/common/misc/ignorecase.cpp
@@ -36,6 +36,8 @@
  *  \author Ryan C. Gordon.
  */
 
+inline namespace dcx {
+
 /* I'm not screwing around with stricmp vs. strcasecmp... */
 static int caseInsensitiveStringCompare(const char *x, const char *y)
 {
@@ -115,6 +117,7 @@ int PHYSFSEXT_locateCorrectCase(char *buf)
     return a() ? 0 : -1;
 } /* PHYSFSEXT_locateCorrectCase */
 
+}
 
 #ifdef TEST_PHYSFSEXT_LOCATECORRECTCASE
 #define con_printf(A,B,...)	printf(B "\n", ##__VA_ARGS__)
diff --git a/common/misc/strutil.cpp b/common/misc/strutil.cpp
index b7f5d3986..196754d3a 100644
--- a/common/misc/strutil.cpp
+++ b/common/misc/strutil.cpp
@@ -36,6 +36,8 @@ COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
 
 #include "compiler-range_for.h"
 
+inline namespace dcx {
+
 #ifdef macintosh
 void snprintf(char *out_string, int size, char * format, ... )
 {
@@ -230,3 +232,5 @@ void string_array_t::tidy(std::size_t offset, int (*comp)( const char *, const c
 	// Can't do this before reallocating, otherwise it makes a mess of things (the strings in the buffer aren't ordered)
 	ptr.erase(std::unique(b, e, [=](const char *sa, const char *sb) { return (*comp)(sa, sb) == 0; }), e);
 }
+
+}