diff --git a/PC/import_nt.c b/PC/import_nt.c
index a31ef30..f0a2735 100644
--- a/PC/import_nt.c
+++ b/PC/import_nt.c
@@ -8,19 +8,26 @@
 
 #include "Python.h"
 #include "osdefs.h"
+#include <assert.h>
 #include <windows.h>
 #include "importdl.h"
-#include "malloc.h" // for alloca
+#include "malloc.h" /* for alloca */
 
-extern const char *PyWin_DLLVersionString; // a string loaded from the DLL at startup.
+/* a string loaded from the DLL at startup */
+extern const char *PyWin_DLLVersionString;
 
-FILE *PyWin_FindRegisteredModule( const char *moduleName, struct filedescr **ppFileDesc, char *pathBuf, int pathLen)
+FILE *PyWin_FindRegisteredModule(const char *moduleName,
+				 struct filedescr **ppFileDesc,
+				 char *pathBuf,
+				 int pathLen)
 {
 	char *moduleKey;
 	const char keyPrefix[] = "Software\\Python\\PythonCore\\";
 	const char keySuffix[] = "\\Modules\\";
 #ifdef _DEBUG
-	// In debugging builds, we _must_ have the debug version registered.
+	/* In debugging builds, we _must_ have the debug version
+	 * registered.
+	 */
 	const char debugString[] = "\\Debug";
 #else
 	const char debugString[] = "";
@@ -31,28 +38,40 @@
 	int modNameSize;
 	long regStat;
 
-	// Calculate the size for the sprintf buffer.
-	// Get the size of the chars only, plus 1 NULL.
-	size_t bufSize = sizeof(keyPrefix)-1 + strlen(PyWin_DLLVersionString) + sizeof(keySuffix) + strlen(moduleName) + sizeof(debugString) - 1;
-	// alloca == no free required, but memory only local to fn, also no heap fragmentation!
+	/* Calculate the size for the sprintf buffer.
+	 * Get the size of the chars only, plus 1 NULL.
+	 */
+	size_t bufSize = sizeof(keyPrefix)-1 +
+	                 strlen(PyWin_DLLVersionString) +
+	                 sizeof(keySuffix) +
+	                 strlen(moduleName) +
+	                 sizeof(debugString) - 1;
+	/* alloca == no free required, but memory only local to fn,
+	 * also no heap fragmentation!
+	 */
 	moduleKey = alloca(bufSize); 
-	sprintf(moduleKey, "Software\\Python\\PythonCore\\%s\\Modules\\%s%s", PyWin_DLLVersionString, moduleName, debugString);
+	sprintf(moduleKey,
+		"Software\\Python\\PythonCore\\%s\\Modules\\%s%s",
+	        PyWin_DLLVersionString, moduleName, debugString);
 
 	modNameSize = pathLen;
 	regStat = RegQueryValue(keyBase, moduleKey, pathBuf, &modNameSize);
-	if (regStat!=ERROR_SUCCESS)
+	if (regStat != ERROR_SUCCESS)
 		return NULL;
-	// use the file extension to locate the type entry.
+	/* use the file extension to locate the type entry. */
 	for (fdp = _PyImport_Filetab; fdp->suffix != NULL; fdp++) {
 		size_t extLen = strlen(fdp->suffix);
-		if (modNameSize>extLen && strnicmp(pathBuf+(modNameSize-extLen-1),fdp->suffix,extLen)==0)
+		assert(modNameSize >= 0); /* else cast to size_t is wrong */
+		if ((size_t)modNameSize > extLen &&
+		    strnicmp(pathBuf + ((size_t)modNameSize-extLen-1),
+		             fdp->suffix,
+		             extLen) == 0)
 			break;
 	}
-	if (fdp->suffix==NULL)
+	if (fdp->suffix == NULL)
 		return NULL;
 	fp = fopen(pathBuf, fdp->mode);
 	if (fp != NULL)
 		*ppFileDesc = fdp;
 	return fp;
 }
-